I think if something is not too serious, its okay to not dicuss it. If you did something major like, totally getting involved, physical relationship, maybe engaged to someone or thought about marrying that person, then you may think about telling the wife.
Proposal and stuff is pretty normal for everyone I think. Anyone who is mature should understand that it is normal for both husband and wife to get proposals so is there really a need to talk about it???? I mean I know that my husband must've gotten some really good proposals.. a doc in US.. who doesn't want that... and I myself got a lot before I married my husband but we never talk about it or we never find the need to talk about it. It really isn't important to us who proposed, what is important to us is that we picked each other and now love each other.
As far as serious relationships are concerned, I would say sometimes its best to not tell. I used to have a friend. He once said, if the past is going to make your future unpleasent then bury it and move on. How many of us happily accept our husband/wife's bad past??? Some might not say anything on the face, but in their heart they know their spouse had done something that they wouldn't approve of. Weigh the benefits of telling your past to your spouse with cons of it. Don't ruin your future for your past.