Of course I don't know your husband, but I do know that there are some men who have a centered, self-aware confidence that lets them avoid jealousy. You're husband may have that quality, I don't know.
Another thing he may understand, either intuitively or through thinking about the situation, is that the relationship you describe does not subtract anything from his relationship with you. In fact, you are happier and more content in your marriage, and so it ADDS to the relationship.
Jealousy can be seen as the result of a zero-sum mindset: whatever affection your girlfriend receives from you must be subtracted from the affection he receives. But that is utterly false. It just doesn't have to work that way at all.
Using that metaphor, your husband may simply not see relationships as zero-sum games. He may want to be with a wife who is happy rather than someone who stays monogamously hetero but who cries secretly in her heart for what she can't have. He may understand that already.
Love 'em both! Celebrate your incredible husband and let him know it. Tell your girlfriend what a special man you're with, and tell her she's wonderful to be with you and, hopefully, be friendly to him too.
Have a great time!
Last edited by EugenePoet; 05-27-2010 at 11:51 PM.