I think that after losing the last patient to a mistake, Foreman is feeling weak and vulnerable and has yet to fully recover from it. Why he stayed there (how many years was it? 3?) with House and just now wants to quit is a mystery. You'd think after a month or two of working with a man like House you'd know whether or not you'd actually want to stay there. But a couple of years is more than enough time to figure that out. And that excuse of "I don't want to turn evil like him" is, as others have suggested, pretty weak; at least for Foreman. So there's got to be more behind it.

At this point I'm not sure if he's gonna stay. This one isn't as obvious as it could be, which is good, because I like to keep guessing. I kinda hope he stays though. It would stink without him.