I apologize upfront if it was discussed and I missed it, but there are so many wordy posts that I can't really get through all.
I haven't seen any post that touches on the fact that the MC is not a "blameless victim" in all this story. What I'm getting at is that the MC is a prime example of savior syndrome to the extreme and he probably had this mentality since he as a kid. Lacey was just the perfect medium to latch on and overdevelop this syndrome. We see it later on everything MC does...with Mia, Christine, Jamie, Bethany, etc and also with supposed enemies, like Isaac, Lorenzo, even Barty at the beginning. The more fucked up a person is, the more MC tries to get involved...so no fucking wonder he's surrounded by a cast of unstable people.
There's plenty of documented cases out there of people even going to the extremes of hurting people in order to be able to save them and care for them, or keep them in a constant state of danger intentionally just to be the hero. On some level, he does this to Lacey, he needs her to need him, otherwise he'd just not have a reason so exist.
MC and Lacey are such a toxic combo for each other even from their childhood. She was an abuse victim and he was the savior, the only savior. She was in desperate need of help and who better to help if not the one that makes helping his whole existence. I don't for a minute believe that he was this normal kid and he got this way solely because of Lacey. He was just too young and forged his messiah complex too soon, too fast and too strong to deny. This was somewhat bad to Lacey too...I'm not saying he shouldn't have tried to help her, but the way he did it left little space for actual growth. She only knew 2 extremes, abuse and overprotective care from a friend that wanted to be her whole world. Whatever she says, it's probably the reason she ended up leaving for college to be away from him, to be able to know who she was outside of him (it failed spectacularly...but oh well).
I've seen a lot of "Why doesn't he leave her ? It would fix everything"...It won't fix a damn thing. Unless MC goes to therapy, learns about his issues and "fixes" himself...if he actually leaves Lacey he'd just kill himself eventually, unless he finds someone else in dire need of saving and ends up not dying because that someone else needs him.
Getting to another thing I wanted to say. For the new readers...don't put too much stock in whatever is discussed in the thread. This is such a complex story that if you hand pick 10 people that read it, you'll get 10 different takes on it. I'm talking about people that actually read it, not the ones that skipped through (or have the media literacy of a small kid, it may sound harsh, but they are out here in force on this forum/thread) and were very quick to throw the label of whore on Lacey/other female cast and the label of weak, simp or victim on MC. If you enjoy reading and like complex characters, go try and make your own opinion on it.