Thank you for more info. It helps paint a clearer picture.
You and Profesa have been together a little under a year. You are nesting partners that love each other. You connect physically, mentally, and emotionally. You want to share/build a life together. You both are new to BDSM and polyamory. You don't really use "labels" on the relationship.
He did break agreements, and you can have a conversation about that. I don't know if it is a deal breaker to you, or a mistake you want to work out because it is still on the learning curve.
But if you work on it? Update agreements. Include BDSM things like NOT allowing other subs to use the name you gave him.
You are also learning there are missing parts to the agreements -- like how fail safes and how to communicate when boundaries are broken. This is basic thing in all relationships to me. Whether in a friendship, or with family, or romances or.... I suggest you address that if you decide to keep going together. You need to be able to do healthy conflict resolution.
You seemed fine with the other BDSM partners. What changed here?
The others were casual play partners and he didn't get all twitterpated with NRE? Is this new lady the first real romantic potential for him?
And now he's messing up because she's already said she doesn't want to share BDSM, and now he's afraid she might turn down polyamory as well so he's ... scrambling about like a newbie hinge who doesn't know how to balance his relationships?
I'm still not clear that she knows you are his nesting partner. Does she actually know now? Or does he tell you he told her, but then really he didn't?
I am just guessing. I think you could ask him what's going on.
Part of the missing agreements might address the poly dating side of things.
You could read
https://openingup.net/resources/free-downloads-from-opening-up/ together. Especially
https://openingup.net/wp-content/uploads/2011/08/Open-Relationship-Checklist-OU.pdf to help shape your updated agreements if you decide to stick around.
If you decide you want to date just him and don't want to poly date any others right now? That's you choosing not to exercise the option. But poly agreements could be designed so both have the poly dating option if they want it.
Even if you don't want "labels" on the relationship? Holding someone accountable to agreements is a basic. Otherwise if they didn't want to be accountable? They could just say "No, I do not agree to that" from the beginning.
If things change, it is their responsibility to check in and say something like "These agreements no longer work for me. I need to renegotiate" to accommodate whatever changed.
I'll be honest -- I expect a Dom to have it better together or at least be working towards that if a newbie. Demonstrate order and control in his own life. Otherwise, how can a sub trust him to control a scene well or feel happy/confident about power exchange?
Mistakes can happen, but solid conflict resolution skills would go a long way in showing he can take responsibility, work to resolve any issues, and do better moving forward.
So again... I encourage you to talk about the things you need to talk about.
For online boards you can try here and on Fetlife, but perhaps you want to also think about local groups also? Since you mentioned being on your own a lot and maybe needing more local friends? Maybe try to join some local poly and/or BDSM boards and groups? It's possible that in pandemic some groups that would do munches, classes and other socials are doing them virtually.
Galagirl