One ended open relationship??

So my husband revealed a kink of his and I'm not totally sure how I feel about it.

He said he likes the idea of me sleeping with someone else, then coming home to him. He doesn't want to be the one doing it, and I'm territorial anyway.

At first, he kinda tried to give me some bs about it helping my self-esteem and all that (which does need a lot of work, but that's besides the point).

I don't really know what to think. He's NOT pressuring me in the least, first all. He just told me about it and wanted to put it out there.

I'm not really comfortable with the idea of sleeping with someone else. I've never been comfortable with guys flirting with me, much less doing anything about it! It's an entertaining fantasy, the whole coming back and bragging bit (and being punished 😝), but I just can't seem to get comfortable with actually doing anything.

We've also talked about needing rules, being safe, things like that in case anything ever DID happen.

I guess I'm wondering if this is a thing with anyone else and how it happened if it was acted on. I'm not completely against it, but I can't get comfortable with the idea either.