For me (assuming I am one), it feels like you're navigating relationships with blinders on.
It's binary. You're either all in, or all out. Small bumps are magnified to feel like catastrophic relationship enders. Friendliness from someone can feel like riding a wave outside of your control.
Unless the consequences don't matter (ie. the person is as bad at relationships as you are, you'll never see them again, etc.), new acquaintanceships can be unpleasant because of the fear of transgressing on someone's values. Meeting new people feels like worlds colliding.
There's a sort of unintentional lethargy when it comes to building relationships - or sharp spikes of relationship-building activity. As was said, it's binary.
And to people who say that Fi Polrs need constant "feedback" because they're inept at reading signals, which is why they have duals who LOLOLOL or
all the time: go away! We're not that bad at reading people's intentions. (even though it'd be fun to have a dual like that).
I hope those aren't just my own idiosyncrasies. Or worse, if everyone was like that.