both blaine and quinn were deeply depressed during their senior years on high school and that's the tea on that.

like quinn lost her daughter, didn't have support, friends, probably her mother didn't understand a shit about her and then she was deeply inside the closet

blaine changed schools to be with the boy he loved but then the boy went away and he started to realize how lonely he could feel there, if it weren't for sam, blaine would've ended up snorting cocaine at a gay bar downtown

like his rendition of teenage dream is enough to illustrate how broken he felt inside, it wasn't even about cheating, he was utterly broken at that point.

both quinn and blaine cheated on their partners and you know what? i understand it, they didn't even want to hurt them, they wanted to feel better at the lowest points on their lives and that's how i understood, their stories may be a little similiar.

both quinn and blaine had crushes on their supportive bi friends who helped them when no one else did I'm truly opening my eyes