Been hanging out a fair bit with a couple of INFPs since touring (separately from each other, that is). A funny bunch. I can easily see why we're not an ideal match for them, despite being close. It's like everything is in place, can be silent together and still completely comfortable, but... there's something not quite clicking. On reflection I think that something is Ti. Can't go into our thoughts with them, at all, without getting a glazed eye look in return. Very different to the INFJ who is fascinated by them, if not quite on the same level.
Disclaimer: not saying a relo couldn't work with one, just interesting cos I've never really got to know any INFPs before.