Kurt: his drug usage. As a daughter of a past drug addict, I know how hard it is to not do drugs (as from what I have seen). It just flat out scares you when he does heroin, seeing the state he's in, his slurred speech, his random outbursts, and strange antics (swaying while standing up, acting weird, or seeming off in general). He never thought you knew, but it destroyed him when he finally found out why you weren't around him anymore, and to make it worse he found out through a note on his counter. While he was out you snuck into his apartment and wrote him a note that told him why you weren't around. He ended up taking months off of his band work to focus on getting better, he ended up coming to you for help. I mean, you have smoked weed before, but it'd never give you the side effects of heroin.
The note:To Kurt
I'm sorry I haven't been around, I really don't know how else to explain it. But I know you do heroin, which is why I haven't been around. I've been through this before, and I don't want our relationship to go down to were eventually I become scared of you. I don't want to do this, i feel like such a coward, but if you wanted to know why I haven't been around, thats why. I still love you.
From Y/n
Dave: his snappy comebacks against you. Like, bitch, it was a joke, get over it. You'll say something like "I bet there's spiders growing in your hair. And he'll be like "atleast I didn't have an abortion at 17". To fucking far asshole. He won't even say sorry, and when he does its half ass, unless he made you cry, that's a different thing. But he'll say he won't to it, but he will.
Krist: his stupid ass opinions. Like, LET ME STAND STILL ON AN ESCALATOR GOD DAMNIT. "Testimony to human laziness, yaddah yaddah yaddah. It still won't change my mind Krusty Krab." He gets really pissy when you make everyone laugh after saying one of your snappy comments.