On paper, INFP - INTP sounds super compatible but irl it's a huge pain in the ass. My best friend of ten years, someone I speak to for ~2 hours a day despite living on different continents, is INFP and it can be a massively annoying. Just don't assume that the lack of communication, general lack of social skills, having their guard up and being private are the result of some trauma from long ago and then take it upon yourself to "help" them through it by forcing them to talk and dismissing any responses along the lines of "that's just how some people are". That's a very easy way to annoy the fuck out of someone of the INTP persuasion and alienate them or at least make interacting with you something they'll go out of their way to avoid.

tl;dr - Try to keep the INFPness to a minimum and don't play shrink.