What should boyfriends and girlfriends (ordinary friends, not lovers) talk about? I am a man.

If it is a relationship between men and women, we seldom meet, so I personally think it is better to be conservative, that is to say, don't say anything. If you hit it off with her, such as growing up together in elementary school, or if you are already familiar with each other at work, you usually care about each other. See each other's cheerful personality, talk about cheerful, optimistic and humorous topics, such as talking about each other's life, work, boyfriend, parents and so on. And you can also say some obscene words in a joke, but it should be appropriate and not excessive. If you are not married or have no girlfriend, I personally think it is better to look at fate. If chatting is congenial, go in that direction. If you are married, I want to remind you not to stay with your girlfriend for too long to avoid unnecessary misunderstanding.