He changed.

My boyfriend and I been dating for 9 months now. We have a big age gap. I'm 21, he's 35. We used to be happy. He used to be sweet. He reply to my messages and calls right away, but after a fight, he suddenly changed. He can ignore me for a week. Before, if were fighting he always communicate with me. His text are short and cold. He even stop saying i love you. I asked him if there's someone else, but he told me there's nobody. He has a problem but he doesn't want to say it to me because he said he will lose me if he say it to me. I asked him if he's married or does he have kids or did he kill somebody. And he said it has nothing to do with it. He said that its his past that its hunting him. He also said its gonna affect my future. I'm between of not wanting to know cause i don't want us to break up, and wanting to know because its bothering me too. I wonder what is his problem? Is he breaking up with me soon? :(