Whenever I'm in class and a book is slammed down hard on a desk/the floor or there's even the faintest sound made, I immediately pick it up. The difference between your reaction to it and mine is that instead of the noise exploding in my head it explodes in my chest. It's really an uncomfortable feeling. I don't know about other INFPs, but it's difficult for me to concentrate after hearing a really loud noise.
Yeah. I definitely notice subtleties in relationships. I know when something's wrong.
I'm an INFP, by the way, if that wasn't already apparent.