randomfox said:
on top of that Raven joining Magneto was absolute bullshit as well. "Oh, dearest brother who has just been crippled by the guy who fucked me once, I shall now abandon you and for some reason beyond human understanding you are OK with this. Later bitches!"
I agree with the rest of your post (although I understood why they did things differently: in this business, you can't just put half the work out there and keep some for the next movie, when the next movie might be made by someone else and ruined. Ideally, First Class would have been divided into two movies, the first one setting things and ending with a small argument between Charles and Erik, but them staying allied, and the second movie would have developed their friendship more (right now they seem to have barely spent any time together, despite how emotionally charged some of these times were) and have the bigger fallout) but not with this.
It seemed clear to me in the movie from the start, except the very first scene they have together, that Charles doesn't get Raven. He just doesn't. And she's frustrated by it, but she has no one else at that point.
Then she finds someone who accepts her, gets her, and likes her the way she is. It's absolutely not far fetched that she'd go with him, although it's made worse by the fact all the rest was rushed around that point too. It would have worked better in the "First Class is two movies" scenario if she was noticeably more on Erik's side by the end of the first movie, and left with him during the second one.
But as I said, I get why they did it that way. It's a bit of a "put everything in there so nobody else can ruin it" that causes the movie to be less amazing than it could have been, but we don't live in a perfect world and it's a damn good movie as it is.