Morgan Riddle was being watched.

Outside the grandstand, while she idled beneath the summer sun, a passer-by stopped, turned and pointed a phone at her, then wordlessly walked away. Ms. Riddle just adjusted her black oval Carolyn Bessette-Kennedy-style sunglasses.

Once inside the tennis match, while she and more than 1,000 other spectators found their seats, people were more direct. “Are you Morgan?” “I recognize you!” “Can we get a photo?” She said yes at least a dozen times that afternoon.

“You’re so tiny!” said Sue McDonald, who had come to the National Bank Open in Toronto with her 19-year-old daughter, Jaiden. She had never been able to get her children interested in the sport, Ms. McDonald told Ms. Riddle, until last summer, when one player on TV caught her daughter’s eye.

“I’m sitting there watching Wimbledon, and I’m like, ‘Come and see this guy,’” she said. “‘Come and see this tall, dark, handsome guy.’ She comes walking in, and she’s like, ‘Oh, who’s this?’”

It was Taylor Fritz, a player from Southern California recognizable for his height (a lean 6-foot-5) and his center-parted, cartoon-prince waves, which he restrains during matches with a Nike headband. Mr. Fritz, 25, is the top American player in men’s tennis, currently ranked ninth in the world.

But he wasn’t the only person the McDonalds were watching during that match.

Every so often, the screen flashed to a young woman wearing a crisp white dress and gold jewelry with blond tendrils framing her face, sitting ultra-poised in the player’s box with Mr. Fritz’s team of coaches and supporters. They looked her up online and soon began following Ms. Riddle on social media, where she shares her life as a tennis WAG — an acronym for “wives and girlfriends,” popularized in Britain in the mid-2000s to describe, disparagingly, a group of preening, partying women attached to soccer players.

Ms. Riddle, 26, doesn’t mind the acronym, she said. She also doesn’t mind being called an influencer, a similarly stigmatized title. She has thick skin and a cleareyed confidence in the life she’s building while accompanying her boyfriend around the world for some 35 weeks each year.

What began in early 2022 with her trying on outfits for the Australian Open on TikTok (a video that has since been viewed 1.5 million times) has evolved into her being hired by Wimbledon to host “Wimbledon Threads,” a video series on fashion at the tournament. This summer, she released two pieces of gold-plated jewelry — a bracelet ($125) and necklace ($175), each with a tennis-racket charm — in collaboration with a small New York jewelry company called Lottie.

In Toronto, one of several women who approached Ms. Riddle between Mr. Fritz’s sets thrust out her wrist, flashing her Lottie racket bracelet.

This lifestyle is not one Ms. Riddle could have imagined for herself three years ago, when she didn’t even know the rules of tennis.

“I genuinely did not have any friends who were interested in tennis, I had no friends who watched tennis, I had no friends who played or wore cute tennis clothing,” said Ms. Riddle, who still does not regularly play tennis. She does, however, watch a lot of tennis now, and wear a lot of cute tennis clothing.

‘She’s Got a Plan’

“I’ll be honest, I was very apprehensive,” said Grace Barber, a senior producer at Whisper, the sports production company that created Ms. Riddle’s fashion series for Wimbledon. Ms. Barber knew little about Ms. Riddle before being assigned to produce “Wimbledon Threads.”

“I just assumed that because she’s, like, really hot and got loads of followers and is Taylor’s girlfriend, she’s basically coasting,” said Ms. Barber, who used the phrase “train wreck” to describe her expectations for the project. She was wrong, she said: Ms. Barber found Ms. Riddle to be hard-working, funny and self-aware while filming the series, which largely consists of interviews with attendees describing their outfits.

“She’s got a really clear directive, creatively, of where she wants to go,” she said. “She’s got a plan.”

The series has already been commissioned for next year’s Wimbledon, provided that “he’s still playing and she still wants to do it,” Ms. Barber said. In July, after Mr. Fritz was eliminated in the tournament’s second (of seven) rounds, the production sped up its timeline, conscious of avoiding online criticism over why Mr. Fritz’s girlfriend was still working at Wimbledon when he was not.

And here is where things can get complicated: In the tennis world, at least, Ms. Riddle’s exposure is still partly tied to her boyfriend’s success.

Many fans who take selfies with Ms. Riddle know her from “Break Point,” the Netflix series that follows the highs and lows of several rising tennis stars. On the show, Ms. Riddle cheers for Mr. Fritz in full preppy, doll-like glam — and, slightly less glamorously, eats takeout with him in their hotel bed — while his story line devolves from a great victory over Rafael Nadal in Indian Wells, Calif., in 2022, to a surprising defeat in the first round of the U.S. Open later that year.

Mr. Fritz has since failed to advance past the third round of any Grand Slam tournament. As such, the “Break Point” crew hasn’t spent much time with the couple for the scheduled second season, Ms. Riddle said. It’s her understanding they won’t be featured again unless he has a big win.

Netflix aside, the difference between winning Grand Slams and not can be financially stark — even for top players like Mr. Fritz, who has already earned $12.9 million in prize money throughout his career, along with sponsorships from Nike and Rolex. According to Forbes, winning the U.S. Open in 2021 translated to $18 million in endorsements the next year for Emma Raducanu, who now models for Dior. After Carlos Alcaraz won his U.S. Open title in 2022, he signed high-profile deals with Calvin Klein and Louis Vuitton.

Still, Ms. Riddle has prioritized financial independence in a way not all WAGs do. Ms. Barber, who is the wife of a professional golfer, said she had seen younger women set aside their career goals, tempted by the lifestyle of financially supported world travel.

“For the first year or so, it’s like a fairy tale,” said Ms. Barber, who is now in her late 30s. “But it’s not your dream. You want to be supportive to the person you love, but you know how quickly time passes, and suddenly it’s been 10 years and you have no career of your own and you’re bored of living out of a suitcase.”

Ms. Riddle has found a way not to be bored — funneling most of her creative energy into a YouTube channel she started this year for longer form vlogs — while also supporting herself. Her income from one TikTok is about five times what she made in a month at her previous 9-to-5 job, she said. (She was formerly a media director for an organization that brought video games into children’s hospitals.)

“I’m really happy with what I’m doing, and I’m making good money,” she said. “People are allowed to make all the judgments they want. A lot of times people have assumptions about me, but then they watch my YouTube, or they listen to me on a podcast, and they’re like, ‘Oh my gosh, I was wrong.’”

‘Not a Bad Deal’

Ms. Riddle and Mr. Fritz met in Los Angeles in 2020, during the early months of the pandemic, on the private dating app Raya.

At first, Ms. Riddle did not try particularly hard with Mr. Fritz, she said. On their first date she suggested they watch “Midsommar,” a fairly disturbing film she had already seen. She loves horror movies and figured that if he couldn’t handle some gory Swedish strangeness, they weren’t a good match. (In turn, he later got her to watch anime.)

Ms. Riddle had just moved to California earlier that year and was living adjacent to influencers, having befriended members of the Hype House, but she wasn’t yet one herself. She had been raised in Minnesota by a public radio executive and a guided tour fisherman, then studied English at Wagner College on Staten Island in New York.

Mr. Fritz grew up near San Diego, born to two tennis players. (His mother, Kathy May, was ranked 10th in the world in 1977.) He joined the professional tour at 17 after winning the junior U.S. Open. Mr. Fritz had grown up fast: By the time he met Ms. Riddle, at 22, he had already been married, fathered a child and gotten a divorce. But because of Covid-19, he was, for the first time in his career, on an extended break from tennis.

Mr. Fritz knew his nomadic life would eventually resume, so he broke it down for her.

“I prefaced it,” Mr. Fritz said, sitting in their hotel room in New York, the week before the U.S. Open. “I was like: ‘Look, this is not how it’s going to be. I don’t have this free time. I’m going to be traveling, like, every single week.’ But I also said, ‘You know, it’s not a bad deal — you can travel all over the world, if you’re up for it.’”

She liked the deal. And he liked having her around. They moved in together after dating for just a few weeks.

“She’s very on me about eating healthy, getting lots of sleep,” said Mr. Fritz, who seems shy off court, but like many players, talks a lot to himself and his team while on court. “It’s the little things that create a healthy routine for me, and that helps me perform better.”

When they met, he was ranked 24th. Now he is ranked ninth. But Ms. Riddle knows how ugly her DMs and comments section — already a place where she is denigrated by some fans for dressing up at matches, selling tennis merch and generally having opinions about the sport — would become if those numbers were reversed.

“If his ranking had gone down, they’d say it’s my fault,” said Ms. Riddle, who sometimes wears an evil-eye bracelet on her wrist, given to her by Lilly Russell, the wife of one of Mr. Fritz’s coaches, who travels with the team and “knows how much” she takes online.

Power Couple

“Power couple,” the Tennis Channel captioned a photo of Ms. Riddle and Mr. Fritz as they walked around Wimbledon in June. Earlier that month, they both became memes after a Paris crowd loudly booed Mr. Fritz, who had just beaten a French player. He shushed them with a finger to his lips, like a kindergarten teacher; Ms. Riddle was seen smiling devilishly behind her pink camera.

She knows she is always being watched. But she is also always watching, able to sense when Mr. Fritz needs encouragement, while also keeping her cool during tense moments. Most cameras can’t see when her knee is bouncing.

“The only time I really get nervous is when I see him getting nervous,” Ms. Riddle said. She knows his tells, like looking at his nails or fiddling with his racket strings. He doesn’t often smash rackets — a stereotype of frustrated players — but when he does, he’ll break them over his knee. The first time Ms. Riddle saw it happen, “I was like, ‘This guy is psycho.’”

Tournaments can be chic; sometimes there are champagne tents and Ralph Lauren-decorated suites and celebrities sitting courtside. During the U.S. Open, Mr. Fritz and Ms. Riddle stay at the posh, wellness-oriented Equinox Hotel New York — he has a partnership with the hotel — and take a Blade helicopter to the Billie Jean King National Tennis Center in Queens.

But sometimes they are indescribably boring. On Mr. Fritz’s final day in Toronto, Ms. Riddle and I spent a full hour watching a court be dried, inch by inch, by vacuum-like machines after a rainstorm. The day before, we had gotten sunburns. Now it was windy and chilly, and Ms. Riddle texted Mr. Fritz, who was waiting out the delay in the locker room, to ask to borrow a jacket. She hoped it wasn’t ugly, she said.

“Welcome to the glamorous life of being a WAG.”

At one point during the delay, Ms. Riddle considered greeting Alex de Minaur as he quickly passed by but decided against it. Mr. de Minaur, the top-ranked Australian player in the world, was playing Mr. Fritz later that day — a match Mr. de Minaur would win. I thought of this moment later, when a couple of tournament regulars described tennis WAGs to me as “political wives,” diplomatically representing their partners around the grounds.

But Ms. Riddle had become a kind of ambassador for the sport, too. Her behind-the-scenes explainer content is a gateway drug for some people, like Jaiden McDonald, the young woman who approached Ms. Riddle with her mother in the grandstand. Within a few months of seeing Mr. Fritz and Ms. Riddle for the first time, she went from ambivalence toward tennis to making a PowerPoint presentation of her U.S. Open predictions. She watches Ms. Riddle’s YouTube videos every single week.

During the rain delay, I searched Ms. Riddle’s name on X, formerly Twitter, and found fan art of her and Mr. Fritz as Barbie and Ken. It wasn’t the first time she had seen the comparison. Ms. Riddle, who has a Barbie-themed iPhone case, had decided to lean into it: When Mr. Fritz appeared on a magazine cover in July, Ms. Riddle commented “hi ken!” on his Instagram.

She likes to joke that Mr. Fritz is her fan, and her fans like to joke about his matches being “Morgan Riddle meet-and-greets.” This started around the time the tagline on a “Barbie” poster (“She’s everything. He’s just Ken.”) went viral.

Ms. Riddle’s publicity team, which she began working with this summer, even suggested “she is Barbie and he’s just Ken” as the concept for the couple’s photo shoot accompanying this article.

As in: She’s everything. He’s just the best men’s tennis player in the United States.