The movie Mean Girls resonated for a reason: everyone who went through high school knows the hell of dealing with that one clique! (If you don’t think your school had that clique, guess what? You were in it!) But most of those types of bullies grow out of that phase as we get older. At least we hope. Right?

Sadly, not everybody leaves the “mean girl” template behind as they reach adulthood. And at least one expert says they believe THAT is at the root of Kylie Jenner and Hailey Bieber‘s recent catty behavior online that’s been directed at Selena Gomez!!

Related: Justin Bieber Officially Cancels Tour Amid Hailey And Selena Drama!

Of course, we’ve been following the sordid story of Kylie, Hailey, and Selena — and Taylor Swift, too — for the last few weeks. Obviously, Selena used to date Hailey’s husband Justin Bieber — and for a long, long time it seemed he’d never get over her… so the bad blood has been stewing for quite a while. But it seemed to explode this month after Hailey and Kylie caught fans attention with some shady social media activity.

Consequences seem to have already come for both the 25-year-old Kylie Cosmetics mogul and the 26-year-old supermodel. Hailey was forced to limit comments on recent Instagram posts after Selenators took to the ‘net to wage a digital war in Selena’s defense! And both Hailey and Kylie have lost a S**TLOAD of followers in the days since the social media spat first broke!

But it may not be enough to get them back on track. At least, not according to Dr. Jenn Mann. The relationship expert and author of the book The Relationship Fix spoke to the US Sun on Tuesday morning, lamenting the cruel nature of Kylie and Hailey’s public behavior towards the Wizards of Waverly Place alum. The expert started by saying:

“It’s very immature. It does have a very ‘mean girl’ high school quality to it. But these are women who have millions of dollars and have successful careers and are grown-ass adults. I think sometimes, certain people, male or female, get a little developmentally stunted.”

Yikes!!

And while Dr. Mann did acknowledge that these “stunted” developmental issues can be related to past traumas, she believes it’s coming from a far different source in this instance: the problem of affluenza. She explained:

“Sometimes it happens because they made so much money at a young age and everyone around them just ‘yesses’ them, so they’re not required to learn social decency. When you are so well known, you’re so famous at such an early age, you are less likely to have people say, ‘hey, that’s inappropriate.’ Like, ‘hey, don’t do that.’”

Dr. Mann continued, calling out Hailey and Kylie for supposedly having no accountability:

“You can kind of get away with more. Nobody stops you. So you don’t tend to end up learning some of these social decencies that one learns as an adult. But it really is a developmental issue to be stunted at a teenage-like age, and doing these kinds of teenage behaviors.”

Ouch! What a rough read!

Related: Kylie Claims Kim Kardashian Is Her Favorite Sister ‘Right Now, But…

The good doc also acknowledged how Justin has such a long history with Selena to the point where it may have left Hailey with some “lingering resentment.” The relationship expert explained:

“Based on interviews that Justin did, it seems like when he came into the relationship and the marriage with Hailey, he was not totally resolved with his history with Selena. And sometimes when that is the case, this other person can harm your relationship, and it can create some resentment.”

We can all understand a bit of resentment. But cyber bullying Selena so aggressively to the point that it pushed her away from social media altogether?!?! That’s next level!!

Dr. Mann agreed:

“I do think that that crosses a line. I think that it’s very understandable to sit and talk with your girlfriends about someone you don’t like or someone your husband or boyfriend or girlfriend once dated. But to post publicly, especially when you’re a high-profile celebrity, it’s just it’s beneath their position.”

Hundreds of thousands of followers seem to agree…

Social media users have steadily come to Selena’s defense this week. Now, the relationship analyst hopes that could be a learning opportunity for Kylie and Hailey:

“You gotta hope that they will reevaluate their behavior, especially given the public outcry over it. Unfortunately, they may reevaluate it in terms of monetary loss as opposed to moral or ethical standards.”

Hmmm…

You can read Dr. Mann’s full analysis on the tricky situation HERE.

Reactions, Perezcious readers??

[Image via Selena Gomez/Instagram/Kylie Jenner/Instagram/Hailey Bieber/Instagram]