I’ll start.
We had great chemistry but different goals. She was religious and looking to marry and thought she could change me, a non-religious person who intends to remain unmarried and childless. I was up front about the lack of religion and the lack of desire for marriage. She was not up front about her intent to change me.
After two months of regular flings she told me we couldn’t see each other anymore, because she wanted someone to go to church with, it was my fault she was living a sinful life (totally), and she was cheating on me with another dude was a Christian.
She decided she wanted to explore polyamory without telling me first. I probably would have been cool with it, or at least given it a shot, had we talked about it beforehand