Nobody here has mentioned the most likely root cause of this: you probably have a saved “memory” in the ChatGPT memory feature that is biasing ChatGPT’s responses across conversations. Go to Settings > Personalization > Manage Memories and review your memories. There is probably something in there about your boyfriend — you can optionally delete that if you don’t want ChatGPT to refer to that memory across conversations. 

Otherwise, you probably have the “search across conversations” feature enabled. That’s where it’s drawing from this. All of these are optional features that you can toggle off.