A neighbor and I are very attracted to each other and like each other a lot, but just want to be friends.  We are both in committed relationships and are happy.

However, whenever we see each other at local gatherings it is difficult for us to just relax and be ourselves. I want to be able to be like an old chum with him.  He is a very interesting person. But I think he is concerned about the possibility of his wife getting jealous of me. We did have a brief romance before I met my current partner.  He, on the other hand, had already been dating his wife at the time. She doesn't know that we dated.

I believe we could be friends if he and I were completely comfortable knowing that our behavior from the point of view of others didn't reveal our attraction (especially while our partners are present). How can I relax and act like an old friend with an ex-lover I still find attractive?