I'm confused here. On the one hand, I'm completely behind following your parents's rules when you live at home.
However... if she (I assume it's a she) can't afford to leave home, how is she going to pay to go on this cruise? I realize a cruise would be a one time expense as opposed to paying rent every month, but the young woman describes it as a larger issue. She says her parents limit the amount of time she spends with her boyfriend.
If that's the case, then this young woman has already ceded a great deal of control to her parents. She's either going to have to accept their rules or get her own place.
Abby's advice is right on. The young woman has accepted this degree of parental control, and she'll have to work within her parents's rules. If she likes the boyfriend more, then she should start making other living arrangements.