No need for conflict
Honestly, my partner has a spouse that I'm.not.involved with. But we're still friends. As far as other women, he's not interested in anyone who doesn't want to date both of us. I'm sure I'll get to point where he goes out without me, but I'm sure I'll go out with our girlfriend without.him at times. Even if he dated a woman separately, he'd never date a woman I couldn't be friends with. He'd actually prefer us to be dating....less pressure on.him to be there for her all the time.
I guess what I'm saying is, there's ways to do it where no.one is ever really left out.