No, you are not being unreasonable. BF's behavior is not cool. There's usually some kind of "messy people" list for people. I might be poly but I would not want my partner to date my mother, my sister, my boss, etc. There's enough people in the world without doing that.
In this case? Your BF putting the moves on your Husband's new potential this way would count on "messy list" to me. He can't give that some space to sort out first and THEN see about dating her later? Jeez! What's he need to prove right this minute? That he can seduce anyone he sets his eye on?
He then went on to say that he didn't like that I was trying to guilt him into not hitting on my friends by telling him that "my internal happiness was tied to his limiting his external choices."
So... he basically wants to behave however he likes without being accountable for his behavior when it dings you and not listen to you complain when it does? Is that it?
I know he isn't seeing a few specific people because M2 doesn't like them. I guess because I'm the secondary, I don't really get the luxury of making my feelings known and having them respected?
ALL people deserve respect. You could be a secondary in some other polyship without him that gives you good manners, right? So this is not
about polyshipping. This is not
about being in a secondary role in your configuration. It is about HIS BEHAVIOR being unacceptable to you because it is ill-mannered.
He lacks in relationship skills, ethics, and/or social maturity.