Wan Meirou had an accurate self-assessment, she loved to put on airs.
Her previous attire was all about bluffing, afraid her girlfriends would think she wasn't cool. Without that reputation, she feared she'd lose her edge and influence.
So, she always dressed as uniquely and flamboyantly as possible.
She wanted to be the "big sister," to let the other girls know that there was nothing she wouldn't dare to do.
However, she was actually very pure at heart, only fooling around with the younger girls.
Just look at Yan Peipei, even younger than Wan Meirou, yet she acted with so much maturity.
It probably had to do with family background. Given Wan Qian's behavior, it made sense for her to turn out this way.
The seemingly most innocent Ye Xinxin was even more composed than Wan Meirou after "that" kind of event, but she was a magnate's princess, used to grand scenes, even if her understanding of the world was flawed.