I don't have anything to offer for advice, but I am glad you posted this. I'm a 49 year old male, and I feel exactly the same. Everything functions, but I feel disconnected. I'm not in a relationship, so there is no issue like you are facing, but it feels so weird. I think I am sexually frustrated a lot, and that might be the source of some of my depression and fatigue, but I'm just not very interested in sex now. I can still do it, and I enjoy it in a way, but it no longer seems worth the hassle.

I wish there was a sub-forum for aging issues like this. I think this whole thing of getting old is getting me down.