I (27M) and my gf (24F) were having a casual night in the bar and were heading to a place to eat some food. My gf was telling me about how she was surviving on having Cup Noodles during her survival days. With this, she jokingly mentioned that she was going on dates just to get food and save it for next day and blah blah. We were laughing about it and she said "I didn't even have anything or any sex with them" and I, in this light moment, jokingly said "Oh really! You sure?".And then, she was fuming and pissed off at me because of saying that and one thing led to another and we fought and left for home. According to me, I didn't mean to hurt her obviously but she thinks I call her 'slut'. So AITA here?