Just think, you have moved from an ordinary person in ordinary life to a Jaguar on the internet. This is a great achievement but not the time to stop. Take a tip from me and don't stop til you reach ecstasy.
Personally I think a good many of the problems which arise between INFPs and INTPs are less about Fi vs Fe and more about Fi vs Ti. The INTP says something which the INFP finds offensive. The INFP looks for the motive -- why the INTP said that -- and attempts to deal with that. In their minds they're trying to deal with the real issue with an emotional source rather than the rationalised smokescreen. The INTP gets annoyed that the INFP has just refused to engage their actual arguments, and is instead speculating on messy emotions which, even if real, are irrelevant to the topic at hand.
The INTP is left feeling that their point was missed (usually phrased as "my point went over your head") and that the INFP got needlessly personal on them probably out of butthurt (at which point Fe may come into play); the INFP that the INTP is being dishonest and/or unselfaware (is that a word?).
NTS: I really need to construct my sentences better so I can do away with all these parentheses.