Welcome to the forum, pippmc. I am a single male (and have been single for a long time at this point), so my perspective may be slightly different, but I'd say that yes it can be just a fantasy. I don't think you should really worry too much about it at this point. It sounds like you have very open and honest communication, your sex life does not suffer because of his interest in tgirls...so, it seems like things are good and he is not at all unhappy with you or his situation. (For my part, I would simply die of happiness if I found a sweet tgirl friend, but if I find a gg friend I hope she will be as understanding and caring as you). If those aforementioned things (communication, sex life) begin to suffer it is maybe THEN that you might start to wonder and worry. For now, enjoy the love you have and don't sabotage it with worrying about what tomorrow may bring. I hope it only brings you continued happiness.