Bit of a problem with one of my partner's lovers
So there's this man, lets call him ... Felix. My girlfriend and I had an incredible threesome with him about 6 months ago. After which a lot started to go wrong between him and me. I was feeling very strong emotions towards him and his primary relationship only really allowed him to have casual sex. I still have no idea how he feels about me - he keeps his feelings hidden (although he recently said that he felt bad after our threesome and didn't want that to happen again)
I decided it was probably best for us both if I bow out and keep things platonic between me and him. My girlfriend and him have been continuing their "casual" relationship since then (although they've only seen each other a few times since then). However, recently things appear to have changed when it comes to Felix's relationship boundaries with his wife. She has now got a secondary boyfriend and it appears that Felix is now open to the idea of a more involved relationship.
Tomorrow my girlfriend and I are going to the city where he lives (my sister also happens to live there). The original plan was that I would spend some time with my sister and also see Felix, but as time is so precious for the two of them I once again decided to bow out and not see him while my girlfriend and him have lots of sex.
So I'm beginning to feel a variety of emotions when it comes to this man. I'm a little bit envious of my girlfriend having delightfully sensual evenings with him. But I wouldn't want to deny her of the happiness that such evenings bring her, and I don't think her not having him would really help me feel any better. And I feel a little guilty that my feeling sad about this might make it less likely that they will enjoy their time together. And most of all I don't want to ruin anything that she has with him! I just wish I could talk to him about this, but last time I tried he simply told me that he wasn't willing to discuss his emotions with me. I feel like my only option is to let my girlfriend get close to him and get some answers out of him for me so that maybe I can find some peace with the situation.
Sorry this is probably quite a rambling post. I was wondering if anyone has been in a similar situation where you have feelings for your partner's lover?