The city we will be living in for his residency is expensive as he is getting into a wonderful program. Count yourself lucky that your boyfriend is able to even consider going to parties with you even if you don't ultimately make it to them.
I think that if these two really care about each other that she should be told to take a moment and ask herself how she would feel if they break up over this and years later she finally researches her religion. Do FaceTime with her when she gets there to drink tea. Full respect and care.