Has anyone had to wait till marriage with their gf even if they had had sex before they met her?

My girlfriend wants to wait till marriage for sex. Idk if she will actually wait or not because she seems to want sex just as bad as me we pretty much have done everything shy of sex...My question is how do you deal with the sexual frustration, and do you think she will actually wait till marriage? i don't think she wants to wait all for her sake...she was very sheltered growing up and her mother has drilled it in her head that that is what is right...do to her sheltered life she is very shy and mood swings drastically. What do you all think of the situation?