What could this be?

So I have an issue (I think) with my current significant other that I didn’t have with my ex husband. I am a pretty jealous individual. I get jealous easily and deal with emotional dysfunction.😅 BUT for some reason when I fantasize my current partner with other girls (specific ones) and it turns me on. Rarely I feel the jealousy creeping in (which is odd for me), but it goes away when I start thinking about it again. I’ll just think of what they’d do to him or he’d do to them. What he’d say to them, what they’d say to him, etc. Its sexy asf.

However, when it’s just regular talk about him and another girl, such as if he tells me of a casual encounter with a girl in real life, I get jealous instantly and feel SUPER insecure.

Like wtf is this crap? What’s wrong with me? Why is my brain f***ing with me like this?

Has anyone experienced this before? Did you find out what it meant and how to work through it?