My fiance constantly lies to me about his past: Thoughts?

My fiancé is lying to me about his past. He refuses to tell me the truth about anything pertaining to it. I’ve caught him in several lies already. I know his past is none of my business, but why lie about it? Especially when you can be lying about anything else in the present. He has even lied about a whole relationship, and I’m starting to see the treats me exactly how he treated her. Is it time to call it quits, correct? Or am I reading too much into things?