I keep postponing the wedding

Last year my Fiancee proposed to me and a month later I found out he was going on Tinder while at work a few months before the proposal. He had tinder screenshots of girls, to this day I still don't know what that was about. We had a huge fight and admitted to me he was curious. He hasn't done anything unusual since but I'm still puzzled by the whole incident and am not truly over it. He seems too embarrassed to talk about it so I don't think I'll ever get the answer of his true motivation. I fell pregnant and it was my call to postpone the wedding. We are thinking of next year but somehow subconsciously, I seem to postpone the wedding as I told him we don't have to and it can wait. I'm a bit afraid that I'll get hitched and the incident will happen. It seems it has tainted my relationship and I can't get past it.