Why do guys end a relationship before it gets too serious?

When a guy asked me out and I told him yes. Then a couple days later he is asking if I wanted to break up with him and of course I told him no I didn't. And he sits there and tells me that he wants to have a long relationship with me. He keeps telling me this and all other sweet things. And I believed him. When he wanted to break up with me he tells me that he is confused and lost. And then he ask me if later down the road if we can date then?He does this when we were just getting serious. WHY?
Why do guys end a relationship before it gets too serious?
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