Open marriage / relationship ?

Definitely open but both would have to agree ahead of getting married.

I would want to know about it at least right after it happened if he was with another girl or even a guy that I didn't already know about.

I think that is fair and I would do the same for him.

Unless it was a regular affair we both knew about and were OK with. Like I could not be married to a guy without being able to be with another girl at all. And most likely regularly. That just wouldn't cut it for me and would never happen if he tried to say no. He would have to be in favor of that even if he wasn't there.

And maybe I would just marry another female. I am really in love with another girl now, but...