Unfortunately I have to agree with the poster who said it usually means their head has been turned. He will be trying to pretend, even to himself (to make himself feel better about it) that it’s not that.. but chances are, it is.
The other thing that strikes me, which isn’t very helpful to you OP I’m afraid, is that in a long, committed relationship or marriage, physical attraction can wax and wane but when people love and care for their partners deeply and there is no one else involved, they don’t admit this bluntly, they just work on getting the feeling back. And this can and does happen. Even together, couples can recognise a lack of spark and address it.. or work through it. Life has ups and downs and sometimes sexual attraction just isn’t uppermost in peoples mind. It’s doesn’t mean they want to split from that person; far from it.
So in this situation OP, and in my broader-than-I-would-have-preferred experience of men, he isn’t confused. He just wants out. Not saying he wants to hurt you.. am sure he doesn’t, but, for whatever reason, he DOES want out.
So do it for him. Tell him it’s over and that you know you deserve better and want to be available to get it. That part is for you to retain a bit self respect; you may not actually feel like that for a while yet. But you will eventually. So let go. Face the pain. Be kind to yourself. Let your friends carry you for a bit.. And in your own time, move on. 💐