Why is he so hot and cold?

I am not a teenager or in my 20's, I am a 45-year-old woman trying to figure out a very confusing and frustrating 48-year-old man. We are both divorced, never remarried. We get along great and are compatible in EVERY way. He is very attentive, caring, loving, and fun when we are together. When we are apart he talks like what we had together doesn't matter and questions the relationship. I back off and he comes on heavy, I am responsive to him when he comes onto me and then he backs off again. What is the deal? Is he playing games with me? Is he a forever bachelor looking for a friend with benefits? Please help...I like him a lot, but I can't take the rollercoaster ride much longer.