Issues with my girlfriend's past

When I met my 30 year old girlfriend 6 months ago,she was open and honest with me about her history.
When she was younger she had slept around a bit,and has had 50 partners,including a number of threesomes with couples.
I had no problem with this at the time,after all,this was all before I met her,she has now chosen to be with me etc.

Lately though I find myself being bothered by mental images and thoughts of her in some of these situations,particularly the threesome scenarios,partly because she refuses to do this with me,as I have suggested.

She says it's because she loves me and doesn't want to share me with anyone

I know she wouldn't be unfaithful to me,and I really want to make this work because apart from this issue we're great together.

I want to be able to get past these feelings of...jealousy,I suppose.

I know I am being a bit silly about this,particularly as my past is much murkier than hers,and the past is the past.

Any advice on how I can stop feeling like this?

Interesting... I recently posted about my husband having the same issues with my past - he knows I did some things with other men, therefore, he brings them up and asks why don't I do them with him, or do them more or at his beck and call, because if I could do sexual acts with people who weren't very close to me, then basically I should be open to do the same things with him whenever he wants because we're married.

This type of thinking leads to an unhealthy and mistrusting relationship. I think your comment "the past is the past" needs to be your mantra. As you said, your past is murkier than hers, and is she bringing it up? Keep looking forward and creating *new* experiences with her. Look at everything as the first time, because it's with her, someone special to you. Please, though, if you can't move past it, don't keep dragging her into your thoughts of her past. Just let the relationship go. It's not fair to either of you. Well, it's not fair to her, really. You're the one being a douche - you knew she was the way she is, and you chose to be with her, right? No offense.

No offence taken. I know you're right. I just wish I could stop being uncomfortable about it.
I know its my fault.
By the way,why won't you do things with your husband that you would with men you weren't close to?
Serious question.

If I were with a woman who had done things with other guys but refused to ever do them with me, that would be the end of the relationship. Unless maybe I had the impression that she REALLY didn't enjoy it the first time and that's why she just never wants to do it again.