This was exactly what happened in my first serious relationship. We were too young and naive to discuss whether we wanted kids until 6 months in. I never really wanted them, but was gaslit so hard by everyone around me that I couldn’t even admit it to myself. I pretended to be on the fence. After the first conversation about it though, I knew we were doomed. I also felt like there was a glitch that could not be unseen, that haunted our relationship and kept getting worse over the following 4 years we were together. My ex wanted biological kids, many of them, and a stay at home wife. Me refusing to drop out of college and give up on my science career did us in, and in a very ugly way. Fortunately we didn’t ever get married. I am thankful every day for that, and that I never gave in and had a kid for him.