We have had dozens of LONG conversations about him sleeping with other people. I am terrified that I will disconnect from him (withdraw, feel hurt, retreat etc) - that will ruin our relationship. Or that he'll decide he doesn't need me and end the relationship.

I (26F) and him (29M) have been in a relationship for two years and we live together. Our relationship is better than I could have ever imagined before we met. Communication and trust are great, sex is fantastic (7~ times a week), we have total value alignment - overall I'd say we're in a really stable place.

Early on in our relationship, my partner broached the topic of having casual sex with other people. At first, he thought it was because he didn't want to feel limited and this was a way he could prove to himself that he's not. (We have matching libidos.) In recent months, we've also uncovered that he misses casual sex (most of his previous sexual partners were purely friends-with-benefits and there was nothing else attached). We had long convos and I realized that right now, I am 1) Not capable of casual sex and 2) Even if I was, I don't want it right now. I gave him the green light to go ahead and sleep with other people because I don't want him to feel limited or to resent me for restricting him. But since I am not 100% comfortable with it, he keeps reaching the same conclusion to "drop the topic" because 1) There may be an emotional fallout and 2) He doesn't have the emotional energy to do all of the work required to manage this fallout.

The first time he reached these conclusions, I accepted them. But then a few months go by, and he asks me if my feelings about sleeping with other people have changed, and the same convo happens. I feel like this is something he wants and my feelings are in the way - and this isn't how I want our relationship to play out (otherwise I think eventually he'll resent me, feel restricted, we'll lose desire, etc)

I am looking for advice on the things that I am struggling with internally along with best steps to get started (do we start small, etc).

I am struggling with feeling conflicted:

1. On the one hand: I am totally on board with nonmonogamy when I look at it theoretically. I like the idea of my partner having experiences without me because I KNOW he loves me and desires me... so I see this as something that will heighten the trust and desire we have for each other since we know that we're unequivocally choosing one another and giving each other room to explore.
2. On the other hand: I think I have some (primal?) insecurities that if my partner is fucking someone else, it will render our relationship inconsequential. Eg. If I am feeling insecure about something, what is the point of doing all the emotional work to make sure I am OK if he's having his sexual needs met already (it's an embarrassing insecurity because our relationship is SO much more than sex). I also fear that him sleeping with other people will hurt me a lot and in response, I will withdraw from the relationship to protect myself from future heartbreak. I guess I am just afraid of nonmonogamy reducing the connection we have with each other.
   

Any advice on how to move forward? I have read Opening Up, listened to Esther Perel's podcasts with couples who opened up their relationship, and watched A LOT of Youtube videos on non-monogamy. I think we do have the levels of trust and communication to make this work... I am just deeply afraid and so is he (of hurting me).