Usually our guts tell us that things are off but we are sometimes in denial or don’t trust ourselves or are lonely and are willing to settle. Sounds like he wasn’t a good relationship material/match for you.

Honestly 4 months is a short time and you don’t really know people in that short time frame. I’d not call a mistake per se, just unsuccessful dating experience that is just part of life and normal dating experience. Maybe some people meet their dream come true right away and never have dating disasters. But those are few and between. Most of us earthy human being dated some questionable characters at some point.

Mistake would be to marry him, financially entangle yourself, move 1000 miles away for him or some other drastic measures. Dating someone unsuitable for 4 months is just what it is