Hmm, this is a tricky situation. From my experience, guys tend to cling to the image that they're the first man in their girlfriend's life, even if they know otherwise. I tend to date very liberal people, but even still all of them seemed to get fairly jealous when I bring up my romantic past. I'm sure your fiance isn't naive enough to think you've never, ever had feelings for anyone else in the past--but like most guys, that's not something he wants to think about or dwell on. A lot of relationships between young people that I've seen operate on a sort of don't-ask-don't-tell policy with respect to each other's past relationships (except for serious issues like domestic violence or STDs that may impact the current relationship). Frankly, most guys just don't want to know. You hadn't gone all the way with anyone else, and you've never felt for anyone else what you feel for him, right? That's what's important. He may have shared the details of his past relationships, but all you'll accomplish by doing the same is possibly causing sad and jealous feelings in him. If he truly loves you and you feel you must absolutely tell him, I'm sure he'll understand and be okay with it, even if he's a little hurt at first. But I think it's unnecessary to feel required to divulge intimate details about one's past to one's significant other (even if you intend to marry them) because it's irrelevant to the current relationship altogether. Don't spoil the unparalleled happiness you can feel in a truly great relationship by worrying about some imagined obligation...just because you're in love with or even married to someone doesn't mean some memories and thoughts are yours and yours alone. Do whatever you feel is best in the end, of course, but I think it's perfectly acceptable to completely disregard your past in favour of embracing your present...and your future.