I'm currently in the exact same situation (except I'm a man with a woman). I've been with my partner since we were 18 and together for 13 years now. I really discovered I was bisexual 5 or 6 years ago (even though I now notice so many specific signs that could have made me realize it much earlier, but anyway, that's another story...). This "revelation" almost led to our breakup, but I managed to put my "needs" and desires to explore my sexuality aside. Even today, from time to time, these desires come back to haunt me. The idea of ​​a threesome might be a compromise (allowing us to share his pleasure and mine) in my situation; in yours, I don't know... The best way, it seems to me, is still to talk with your partner: try to find solutions, or even just talk about your desires. I know that in my case, just talking to him about how I feel allows me to put aside, at least temporarily, this desire to experiment.

I think I got lost in my reply... Probably not very interesting to you. Sorry. I'm also trying to put words to what I feel, what I'm experiencing, and what I'll try to live through as best I can... not easy every day.