Me and my girlfriend have been dating for about a month now. She has an ex-boyfriend who cheated on her while she was 19 years old. While we were walking off the uni campus, we started joking about polygamy, mind you we are both definitely monogamous, and we were bouncing off of each others jokes. I made a stupid joke about her cheating ex, it was something along the lines of "Don't worry I'm definitely monogamous I would never be with someone else other than you, and I know you would never cheat on me because you know what it feels like because of your dumbass ex." And she laughed for a few seconds but then said it was a tasteless bad joke. We didn't fight or anything and I immediately apologised. She said it hurt her a little bit but it's okay and said it was kinda funny but also hurtful. I got really angry at myself and also felt really sad and I felt like an asshole. Since then I apologised a few more times and she said it just hurt in the moment and she doesn't feel sad about it anymore. She said something little like a joke wouldn't hurt our relationship and she still loves me the same as it was before. We came back home and made out, hugged eachother and she told me I look so sad and reassured me that it's fine and it has passed. But I still feel like shit and I feel like I disappointed her with my stupid joke. Do you think this mistake of mine was something that hurt our relationship?