To be concerned about DP "fantasy"

Fantasy literally means imagining an impossible or improbable thing… I would be uncomfortable if my partner was uncomfortable about the literally imaginable world I construct in my head. I would fully attribute it to my partner’s insecurities and suggest he gets some support with these. Kinda similar to people getting upset with their partner because they had a dream that the partner cheated on them. That’s fully on the person who saw the dream, in my opinion.

I fantasise about killing people. Doesn't mean I'm ever actually going to do it.
You shouldn't have asked the question if you didn't want to know the answer. And it's pretty tame fantasy tbh.

I think it's fine to have individual fantasies provided both parties understand that both of you need to be fully consenting and on board for them to happen. The fact she's got this fantasy wouldn't bother me in itself provided she's happy not to explore it given that you wouldn't feel comfortable with it and she's not putting pressure on you in any way.

I mean…

The whole point about fantasy is supposed to be that it’s not run of the mill and is outside the scope of the relationship.

Neither of you is wrong.

I personally can’t think of anything worse than a threesome which is why I wouldn’t open this sort of discussion. Ditto anal sex and various other sexual things which some people crave and others can’t stand. I am not interested in any of this and can’t be arsed (pun not intended) to indulge in any sexual activity which I don’t want to do to keep someone onside. I gave up being bullied into doing things I didn’t like to keep partners happy many decades ago and I wouldn’t go back on that now because someone wanted to try something. If they want it that badly they can fuck off and find someone else to do it with. I never understand why people ask this question when they aren’t prepared for the answer.

If my partner had ever asked me to do any of this I would have to have a difficult conversation about it. As he hasn’t I wouldn’t invite it. But as you have opened that can of worms voluntarily I don’t think you can then be surprised and shocked at the outcome. Play silly games, win silly prizes etc.

Try not to be the thought police.

Lots of people fantasise about all sorts of things, and fantasies are just thoughts, not reality or fully formed intentions.
It doesn't in any way mean that they're going to non-consensually bring them in to the relationship.

Rape fantasies, for example, are very common - that would not mean that the person actually wants to get raped - the safety of a fantasy is very different.

Maybe reframe it that it's a good thing she feels comfortable talking to you, and try not to shame her when she hasn't in fact done anything wrong.

It would make me uncomfortable too. I'm monogamous and wouldn't want to bring anyone else into my relationships, and I'd be a bit wrongfooted if a DP wanted to do so when a monogamous relationship had already been established.

I don’t see any merit in discussing each other’s fantasies if you’re going to get bent out of shape if your partner has some.

She hasn’t said she’d like to explore outside of the relationship, she said more or less the opposite: she likes the idea of exploring it with you, but since you aren’t interested, she isn’t either.

"We were discussing our fantasies"

So the problem here is that she's the only one that actually has a fantasy to begin with. You were just asking her about her fantasies.

She has the most common fantasy ever, you really don't need to be worried.... I mean, what were you expecting?

It's a very common fantasy, and one you are clearly not comfortable making a reality.

That is totally okay and neither of you is in the wrong.

Honest conversations around intimacy are important

Why would you be concerned? I would only be concerned if she then decided to go ahead with it despite your opinion.
Don't ask a question if you don't want to know the answer.

You asked, she told you