Why all of a sudden does a man stop being interested in me?

A guy I met a year ago was interested in me and I was married. He always flirts with me ask me if I’m still married. Then after a few months I finally decided to get a divorce. Then he finally asks me if I want to go to lunch on Valentines day? I said I would love it and he said great its a date then he said does that mean you’ll be my valentine? I said yes I will. Then he ask when will you be divorced? Do you want to date? Do you have someone in mind? I told him a few days later that I would like to someday date him. Then it all starts. He said you would date me? Wouldnt that be difficult? He said that he wants marriage and children and he dont think I want that? I told him that maybe if I was younger and he said age is not the problem just the fact that were on to different things. We go out on our date something I worked very hard to get ready for and he told me I would get to see his apartment when I pick him up. I go pick him up and he never showed me his apartment he was sick the whole date lasted 1 hour. Now somedays he is really nice and talks to me alot and other times he acts like nothing. He is totally driving me crazy. What is going on with him. I know he wanted to be with me for a year why is he acting so strange? What should I do? Before all of this happened I tried to stay away from him for a few days and then out of the blue he calls me text me told me he misses me. Then when I do that he wont even text me back anymore.