There are people who face more issues to disengage from certain feelings than others when it comes to sex there are lots of reasons for that. I recognize that i have double standards and a lot of issues regarding this subject and i can't put my finger on where exactly it's the problem. As an INFJ and specially as a judger, we can be promiscuous as anyone, but they need to know where they are before, and make themselves a mindset, or something like that. As a judger, i need to see if the relationship is serious or not, if there are strong feelings behind or not, and if there are, it doesn't matter how much the other person may see our relationship as just a "fling", she will know my feelings, no matter what, and she will know my intentions. Not because i'm a clumsy romantic (which i am anyway lol), but because i've already made my mind and it's stupid to keep those feelings hidden, i would fail to trust her, and things will get "stuck" and i would be doing unnecessary harm to myself. It doesn't have to be verbal anyway. Maybe perceivers don't to have this "i need to know what's going on" as marked as judgers, they're more flexible, however, there's always room for exceptions, and i'm mostly rambling here.
As i study the Enneagram i can see that as a 4 of the sexual subtype (Competition/Hatred is the keyword of this subtype), these issues that surrounded me, like idealization of love, jealousy, ambivalent feelings towards sex, going grossly over-the-top with emotions, and constant self-torture for my out-of-reach romantic interest, are indeed inside my psyche, and not an outside influence.