wastinaway,
my response to your 3 points is as follows:
1) probably because if someone has been co-habiting for a significant period of time, marriage doesn't really add anything more to their relationship. Yet, if that person has undertaken marriage vows after co-habiting for some time, then I presume they will think that marriage does add value. Therefore, marriage becomes disappointing.
2) and 3) if someone has no experience of sex prior to marriage, they have nothing to compare their current sex life with. This may well mean that they will be happy with what they've got. Also, I think nowadays, the marriage of two virgins is a pretty much extreme situation. It is most likely to occur between religious couples. Their faith will put an extra emphasis on them staying together, no matter what their marriage is like.
I think it is interesting the way our society puts so much emphasis on staying together. I've heard people talk about splitting up, as if living alone is some kind of hell. Even after only a few weeks together.
