Do guys lose interest that fast?

I'm talking to this guy and we've been in a past relationship before and it didn't work out then and im trying hard to make it work now... we've been "together" a few times now and doing that has never been a problem for us. I am telling him all the time that I care for him and have feeling and want to be with him. He was saying that until a few months ago. He says he still likes me but when I ask him to tell me how he feels about me, he tries to change the subject. What does that mean?
Do guys lose interest that fast?
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