She had the real love story
Okay so Annette and Sebastian were kind of sweet, in theory. We all fantasize about being the *special girl* to change a narcissist like Sebastian. What girl hasn't tried to seek validation by trying to change a fuckboy? But they weren't in love, they were infatuated with each other. That's it. Name one time they had a conversation of substance in the movie. You cannot. It was just a tête-à-têtebetween the doe-eyed virgin and the smoldering bad boy who would play cat and mouse with each other the entire time. They literally just made googly eyes at each other and had good looking sex (which was MISSIONARY might I add, so it wasn't exactly steamy) while music swelled in the background. That is not love, that's just sexual tension with soundtrack. At the end of the day, they would not have lasted at all.
The real love story is between Kathryn, and well, herself. She's the only one in the movie that's got an unshakable confidence. Sure, she got outed in the end, but that doesn't exactly mean she's self-loathing. She was the only one who wasn't actively seeking love in the movie because she's doing her. Let's be real here: that kind of self-love would have lasted longer than any of the romantic relationships in the movie. If you're still in a long lasting relationship with someone you met when you were a teenager, I absolutely am judging you because teenagers are disgusting and cringeworthy. Self-love starting at a young age is way healthier.