As an NF, I love to fall in love and am guilty of idealizing the object of my crush. When I was in high school and early college, I would get swept up in a moment with a crush and cheat on whatever boyfriend I had at the time. This inevitably led to a big mess and a lot of self-loathing on my part, and I knew I needed to shape up. Especially since meeting my current partner, I've been very watchful of myself and have overcome that side of me. I read an interesting passage in a relationship book about how when two people have a mutual crush that develops into the opportunity for an illicit relationship, we are really in love with ourselves because we are in love with the way that the other person views us. (Kind of a big narcissistic love fest, because the guy you're crushing on who has a crush on you is probably in love with your idea of him, too.) So now when a little crush comes up for me (happens maybe a couple times a year) I have gotten very good at imagining a connection with the person in my mind only. I allow myself to daydream, but I absolutely forbid myself from acting on the crush in any way. It eventually dissipates, and I come to see the person's faults and how silly I was for feeling that way and am glad I only acted on it in my head rather than in real life.
All that makes me glad I'm not in a relationship with a fellow NF. Our types can be very, very admirable, but I think sometimes we have to be vigilant because our passionate hearts can lead us astray!