As Desiree Frederickson, 40, started watching the third season of “The White Lotus,” the show quickly became personal for her. “I was immediately triggered,” she said.

The HBO series follows guests and employees around the White Lotus, a fictional resort chain, with this season set in Koh Samui, an island in Thailand. Among the gaggle of affluent guests are three women in their late 40s who have been friends since elementary school but now live different lives. Jaclyn is a Los Angeles-based actress (played by Michelle Monaghan); Laurie is a divorced lawyer in New York City (Carrie Coon); and Kate is a Texas housewife (Leslie Bibb).

(Warning: Spoilers ahead.)

To one another’s faces, they are supportive and complimentary. Behind one another’s backs, they are petty, gossipy and competitive. In varying combinations, two of them pair off to talk about the third, which is a dynamic resonating with viewers across the country.

“I have been in this exact scenario so many times over the course of my life,” said Ms. Frederickson, who lives in Fontana, Calif. “I’ve been in groups of threes, and I feel like sometimes I am closer to one person over another. Or I have been the person in the middle who they talk about, and I find out later.”

In the last year, she has had to navigate the complexities of friendship triangles. Ten months ago, when she had a baby, one friend was angry that another got to see the baby over FaceTime first. She is also trying to make amends with a friend who feels left out because Ms. Frederickson and their other friend hang out more.

“Let’s just say this show is validating,” she added, laughing.

Lisa Morse, a clinical psychologist in Manhattan, said that “in our society, so much about friendship is so sanitized. You see people’s Instagrams, and they are all on these girls’ trips and everybody looks happy, and it’s so flawless.”