Wow! That’s tough. You never know what lies in wait for you.
If you stay there, and it doesn’t get better, then you could stop it later. The other thing you can do is present it to him as a problem, something you’d like to work on. Communication is the key to every relationship.
I was in two relationships where I lost attraction to my partner. I eventually married a woman who I thought was the hottest woman I’d ever been with. That caused problems when we stopped connecting (relationship-wise), years into the marriage. For her, it was as if I didn’t care because we no longer shared much, and for me it was like she didn’t care because she didn’t seem interested in my body any more. However, after a couple of years in couples therapy, I have to report that she actually does like my body, and I no longer have to hide how much I am into her.
I’ve found that breaking up is the worst thing there is, but eventually, someone else came along that I fell in love with. It was painful in between. Although, with me, there wasn’t that long a time inbetween.
I’m not sure exactly why I lost my physical attraction to those two. It could well have been a symptom of some other loss of connection. Maybe I thought we no longer shared as much as we had, but rather than thinking that, it got transferred into the feeling I was no longer (physically) attracted to them.
I think it can be hard to sort these things out. Perhaps our bodies are telling us something that our conscious minds are not willing to admit. I have one friend who got married because she wanted to settle. Later on he cheated on her, and she realized that she never should have married him.
You can’t know what will happen. I think that if you want it, eventually you will find someone you want to make the compromises that are necessary in order to have a relationship with that person. And do it joyfully. It is painful to let go of someone. Perhaps you can remain friends. Perhaps not. Perhaps later you will be friends. Or maybe he’s feeling something similar to you. All I know is you have to talk about it, painful as that may be. If you don’t, then you have no chance of working it out. But this is not the kind of thing you can hold back on and hope it will change. It won’t change by itself. You have to work on it. If you’re not willing to work on it with him, then it probably is time to let go.