This is always the case and they’re being completely disingenuous in acting like it’s really just weekend visits with proper boundaries lol.
If a female roommate’s bf is over too frequently, it’s “when” not “if” he’ll move in. Women get a man and lose their entire mind. They’re not telling him no if he wants to move in, and for him to be there that much in the first place, he doesn’t have a stable place of his own.