Just wanted to add - we had a talk about this (e.g. moving forward with this, moving in together etc.)
He's really happy that I've given them more freedom (2, maybe 3 nights a week, generally sharing weekends and no limitations on meeting secondaries on days or eves when we're not together). We're also going to continue to hang out, all three of us, every two weeks or so because we're all fond of each other and it helps avoid seeing the third person in a 2-dimensional way, I find.
He is uncertain if he can commit to generally being away only 2 nights a week if we live together, because until recently he used to compromise his own needs by default and get resentful, so he's reluctant to commit at this stage which I totally understand, but it's also a non-negotiable for me. I don't want to sleep alone nearly 50% of the time if we live together and I don't want another "proper" relationship. I'm out lots and not at all clingy, but I need companionship. He wants time to consider and we're both thinking and talking about it; we have at least a year before it happens, probably longer, and it's quite a luxury to take time figuring this out. I've also shown him this thread and told him: "I thought I couldn't be in a full poly relationship, I'm still not 100% sure but I'm willing to try it out because if it doesn't work out I lose you, but if I don't try I'll also lose you (even if you stick around, it won't work). So at least this way there's a chance to stay together and have this journey and give you a chance to have what you need, even if it causes me discomfort at times... All I'm asking - when we talk about living together and the ways you might be able to help me manage living with a poly partner while still meeting my needs - is that you at least consider the possibility of doing the same." He is definitely understanding and open to the idea.
The issue for me is, companionship and life partnership are what I need from a relationship; if he decides it's not for him I'll need to break up, so I'm hesitant to keep taking difficult and scary plunges and make a huge emotional investment in a relationship that might have an expiry date, especially after going through so much together. I have enough resentful friends who kept waiting for their partner to "be ready" to live together/have children etc. and are now in their 40s and bitter. Sometimes it's best to acknowledge different life goals or personality differences and break up fondly instead of trying to mould each other in your own image. On this journey I am learning what is motivated by fear and what is a genuine, conscious life choices and life goals... I guess some of this is about how far we can both compromise, considering our differences (he needs more freedom ; I need more security. He's poly and I'm emotionally mono, he's more "feral" while I'm domesticated, etc.)
Time will tell, but so far we've having really good open and honest communication about it all for the first time in a long while, and hot sex, too