All I can say here is that I think that you're entirely right that there is a big difference between play partners and long term partners, that it's ok for there to be different boundaries for each, that it's not ok to constantly expose your kids to new partners who then disappear, that it's not ok to break boundaries, that it's not ok to constantly change boundaries to suit one person's desires one minute and then change them back to suit their insecurities the next minute...
You're entirely, completely right. There's no rubix cube here that I can see, no puzzle, except for this one: why can't he see all the things that I listed above and then be strong enough to adjust his behavior accordingly even if he doesn't like it, even if it means he can't have something he wants right away on the one hand or that he has to allow you the possibility of something that will make him jealous on the other?
Only he can answer that.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.