Something has to give.
Quinn knows it; she can feel it in Santana's growing tension, in Brittany's dimming sunniness, and in Finn's steadily wandering eye.
Brittany's spending more time with Kurt Hummel of all people, Santana is spending more time with Puck, and Quinn is trying to spend more time with Finn without having to kiss him, but it's not working well.
(During that time, she learns how to use kissing as a weapon, to complement her shield of religion; she can get Finn worked up enough that he stops looking at Rachel Berry for a few days, then claim a prayer break when he starts to get handsy. It's working for now, but she doesn't know how long that's going to last.)
She feels so plastic and brittle these days; everything is a mask, and she's started to forget who the Quinn underneath it is. Brittany helps her remember, sometimes, when she's laying in bed with her and Santana (but it doesn't always help to remember that person. Sometimes it just makes her wonder if she could have someone love her like Santana loves Brittany, if maybe she were true to herself like Brittany always is), but it disappears like morning mist the second they're out of bed and she and Santana put on their school masks.
It builds up.
She watches Santana-and-Brittany be so fucking perfect (and yes, in the back of her mind she knows that they're a lesbian couple in one of the most homophobic parts of the country, but she doesn't care, because if she had one person, just one person look at her like they look at each other-) and Finn look at Rachel, and then Puck look at her, and it breaks. Whatever it is, it breaks, and she texts Puck, demanding he come over.
He brings a pack of wine coolers, and smiles (it's 50% "sex shark Puck", 50% "friend Puck", and 100% what she needs right now).
She's not usually a talkative drunk, but between Puck's calm waiting (for her to get drunk, and she knows it but doesn't care) and her own insecurities bubbling up, she tells him just about everything, only she calls it all "feeling fat" (Brittany and Santana make her feel fat, Finn makes her feel fat, even Rachel makes her feel fat).
He just looks at her, and says, "you're not fat."
He means it literally, but drunk!Quinn takes it figuratively. In that moment (and in the half-hour after), "you're not fat" means "you really will get out of Lima", it means "Finn will realize what an idiot he's being", and most of all it means, "someone will love you like Santana and Brittany love each other", and after that-
She half-forgets about it. She was drunk enough that all she really remembers is a flash of pain, and Puck saying he "would take care of it", and she doesn't even remember what context he meant it in. She knows she slept with him - why else would the pain be between her legs? - but it's so easy to ignore it. He doesn't bring it up, she doesn't tell Finn, and life goes on.
Life goes on - until two blue lines on a white background says it doesn't.
(She breaks down. An entire night is spent sobbing into her pillow and going over and over everything she's lost, everything she could have had. The list repeats endlessly in her head - social status, a chance of getting out, having her first child be with someone she actually likes - until she finally falls asleep out of sheer exhaustion, and when she wakes up the next morning, it all starts over again. That entire weekend is spent crying and hiding in her room, ignoring everyone's texts and calls. Only on the last day does she start to form a plan, and it takes her a week to come up with a plan that's going to make this work for her, at least as much as pregnancy will ever work for any fifteen year-old.)
Finn is easy to convince.
All she has to do is play on how dumb he is, and let her feelings out just long enough to fake a breakdown in front of him (and it's scary how close to a real breakdown it is; she feels her plastic thinning and warping at the edges).
Puck is... harder.
It's obvious that Finn told him - and how dare he, but that's something for another day - and she lashes out at him. She knows it's lashing out, and she knows it's heavy-handed for her, the queen of subtle manipulation, but she blames it on the pregnancy hormones (and god, it's hard to even think of it that way, to think of something - someone - growing inside her). She can't help it. They had a chance for something good, if only -
(if only she weren't sick every time she touches a guy, if only she hadn't started out dating his best friend, if only he weren't sleeping with her best friend, if only if only if only)
- but "if only"s won't help her now, and Noah "Cougar Hunter" Puckerman is not the father this child needs. She's made her choice, and she's standing by it.
The thing with Mrs. Schuester is so weird that for one second she forgets that she's completely screwed her life up. She takes the vitamins (and the advice, and anything else Mrs. Schuester is willing to give her, because here is someone who isn't judging her. Here is someone who just wants something from her; territory she's familiar with) and when she gets home, she hides the vitamins in her purse and puts on a fake smile for her father. (That, too, is familiar. She can't remember the last time she genuinely smiled for anyone, least of all her father).
The next time Santana texts her about "studying", she turns her phone off and kneels in front of her bed, praying (she tells herself she's praying for her own soul, but really, she just can't take the way she feels around them on top of being pregnant; it's too much sin all at once, and she's already drowning).
Santana stops texting. Brittany doesn't. It doesn't matter either way, because after that, things really go to shit.
(She doesn't even apologize to Jesus for describing it that way, the way her parents would have wanted her to. "Shit" is the only way she can possibly describe her life at that point, and she dares to think for a few seconds that if Jesus really cared about her life, maybe he wouldn't have let her get pregnant the first time she had sex).