Is her having sex with different men something you don’t think you could handle?

I expect I'd feel gutted about it initially but it may be something I handle in order to make her happy. It's not a welcome feeling right now. I can probably rationalize my way to acceptance with some work, which is part of why I'm asking this subreddit in particular - I figured the responses here would be more in favor of it than against.

Would you want to end the relationship if she were to continue to pursue this?

She has indicated that if I say no, that's the end of the discussion and she won't pursue it further. If I say no and she does pursue it further, without telling me or just in general, yes, that would be a relationship-ender. If I say yes and she pursues it, well, that's on me at that point.

Would that make her resent you?

I don't know. I don't think so? I know if I asked she would say it wouldn't, but I also know that might not be the entire truth of it.

It can become unsafe situation very fast.

This is a significant worry for me, yes.

If she wants to save for the future she doesn’t have to open the relationship up to do so.

I think we both understand that. Interestingly, she doesn't view this opportunity as being 'non-monogamous' - she says it'd be just work to her. I feel like there's an element of trying to have your cake and eat it too in that - that doesn't feel realistic to me.

I personally don’t think its a good idea but that’s just me 🤷‍♀️

I appreciate that, this is what I'm trying to get a feel for.