less Relationship- "A downhill spiral?"?

It may be that he has some kind of a physical problem, an erectile dysfunction. This is not a subject most men will discuss. Do some research, and see if there are any things you can do to help him if this is indeed the problem. If it is not the issue, and he is not willing to try and give you the affection you need, it may indeed be time to move on. Intimacy is a critical part of any relationship. Without intimacy, you are not going to be fulfilled, and you will not be happy in the rest of your relationship. Good luck.