Yeah... some people prefer to be exclusive, and if he can express that in a mature and respectful way (i.e. "I'm just not comfortable sharing" vs "well I guess if you have to you can cheat on me," or whatever other passive-aggressive bullshit), then that's a valid choice, and you have to really talk about where to go from there -- whether one of you is going to compromise, or you're going to end the relationship.

Personally, as a submissive in an open relationship, I am not willing to let my husband dictate what I do with my other partners, unless it is a matter of safety or honesty. IE I understand if he wants to ask me not to do extreme edge-play, because he doesn't want me to get hurt, or if he doesn't want me to lie about being married, which I wouldn't do anyway because that's disrespectful to everyone involved. But honestly, I don't think it's any of his business whether I'm dominant or submissive with my girlfriend. He doesn't have to watch or think about it if he doesn't like it.

I understand that different couples have different ways of doing thing, but I think that even the strictest TPE relationship has to make some adjustments to being open or poly if that's what the couple decides on. I think it's ridiculous to say "okay, you can see other people, but I get to tell you exactly who they will be and what you will do with them." To me, a relationship that's genuinely open for one partner -- he gets to do what he wants with whomever he wants -- and not for the other -- she gets to do what he's okay with her doing -- raises some consent issues.