Kristin Cavallari, 37, is dating a 24-year-old; a 13-year-age gap that has led to jaw drops and judgment.

Earlier this week, the Uncommon James founder went Instagram official with Montana Boyz member Mark Estes in a selfie of the pair under a beach cabana. She captioned the post, "He makes me happy" with a red heart emoji. Cavallari's dating life was first detailed on the MTV reality show "Laguna Beach," which traced the lives of high schools in Orange County, California and later on the popular spinoff "The Hills," and the 2019 revival "The Hills: New Beginnings."

People were quick to reply to the post with jeers: "Homeboy was 6 when 'The Hills' aired on MTV," one Instagram user commented. Another added: "Your kids need a step dad, not a big brother."

On Friday, Cavallari shot back at critics of her dating life in a TikTok video.

"When they’re all up in arms that I'm dating a 24 year old. Andddd?" the mom of three captioned the video, as she mouthed the words to a sound that said, "So what are you gonna do about it?"

TikTok users expressed support and happiness for her in the comments section.

The relationship is reminiscent of the now-defunct courtship between Olivia Wilde and Harry Styles, whose 10-year age gap similarly caused a commotion. What's true of that relationship is true of this one: the woman is older. This one-sided reaction, experts say, is about who is leading the age gap.

Ultimately, it's the women who bear the brunt of the criticism in these heterosexual, age-gap romances, as depicted by the label "cougar," which paints older women as wild animals on the prowl.

"It's women who always bear that social attack and backlash," Janet Morrison, a certified sex and relationship coach, previously told USA TODAY. "Whether it's older or younger – she wants the sugar daddy and the money. Or if it's a woman dating a younger man, it's all about the sex. She's 'preying' on someone because she can't get someone her own age."

Part of this mistreatment may stem from unfamiliarity, Morrison acknowledges. Despite the prevalence of women-led age gap relationships in Hollywood, this dynamic is relatively uncommon. In most cases, however, it's a classic example of the way we disparage women for their choices, especially when they don't align with what we view as "traditional." 

Kristin Cavallari and our problem with older, powerful women

The media tend to portray age-gap romances in a one-dimensional manner: the older man, wealthy and stable, has the power – socially, financially and even sexually – while his attractive, young, dependent "trophy wife" offers one thing: beauty.

We're culturally reluctant to accept the reverse: an older woman, or even a mother, pursuing a younger man, because it conflicts with our gendered, sexist norms of who should be "in control." 

"If the woman is much older, people make assumptions like, 'Does she wear the pants? What does this mean about her need to be in charge or her huge sexual appetite'" – judgments that sociologist and sex coach Jenn Gunsaullus previously told USA TODAY are normalized when applied to men. "When you put older women in that same position, people don't know what to do. It doesn't match their expectations, so they judge and stigmatize it."

It's why terms like "cougar" – with no male equivalent – are weaponized to shame older women in these relationships. According to Sarah Hill, an award-winning psychologist specializing in women, health and sexual psychology, this public discourse is also yet another example of suppressing female sexuality.

From 'sexual' to 'sexless': The double standard of aging for older women

Some would say men get more attractive with age. As the years, and their experiences in the world, go on, they are wiser and more stable. They become more dependable and therefore more desirable.

And yet ironically, the same qualities we value in men become the very attributes that make us uncomfortable with older, powerful, independent women – who are perceived as "intimidating," not "beautiful." Or "maternal," rather than sexy. 

Our cultural fixation on youth is to blame, according to Morrison, especially with a beauty industry that peddles wrinkle-free, anti-aging appearances. "Younger is more beautiful according to our society, so people generally get creeped out when women go after a younger man."

That's why one of the biggest steps to normalizing women-led age-gap relationships is "elevating the power and voices of older women and what they have to offer." More grace and flexibility, Gunsaullus says, is needed to empower older women "to be more real. They can be more authentic and open and still be considered powerful and wise without being demonized as unattractive or masculine."

Important:Kristin Cavallari cut her 'narcissist' dad out of her life. Should you?

Older women, younger men can have fulfilling relationships. Here's how. 

People have been slow to embrace age-gap relationships. It's assumed that an older woman and younger man's romance is destined to fail, or perhaps it's the consequence of her midlife crisis.

"You have to be confident in your relationship," Morrison says. "The biggest external factor that influences most of these relationships is not the age but the response and acceptance of the relationship by peers."

Contributing: Jay Stahl and Jenna Ryu

How to make it work:Age gaps in relationships can be tough.