You should probably read my responses more careufully. It's not so much what I think of other people's behaviour that matters but rather, the reasoning behind what is said. Simply using the 'my life, my choice' line (or something similar) is not presenting anything of substance. It does not take into account the various issues surrounding her situation. The point I was trying to get across with my criticism of that line is that it isn't as simple as 'my life, my choice.' So it doesn't help her at all to make it seem that simple when it isn't. Think first, blab later.
As for the maturity thing, you're not really being precise about what could be done. All you're offering are vague suggestions which could be interpreted in a myriad of ways, just to refute my previous comments? Comments which I had intended to help her with. That hardly helps this thread.
So you want her to consider her choices, needs and her family's needs? If that was all that she needed to do then I don't think she would need to make a thread about it. I mean, she would have a better idea than anyone here as to just how badly her parents would react to her bf going on the trip with her. So she just needs to decide between making her parents happy by sacrificing her needs this one particular time, or considering only her needs and going with her bf even though there are certainly many other opporunities when they could spend time together. But of course, this is assuming that the situation is as simple as you make it seem in your maturity comment.