Agree with pmj85 - don't give it too much thought. If anything, MBTI could be a tool to better understand each other's expectations and behaviors, but it can easily be taken too far. I think it can be really detrimental when people start pigeonholing each other with, "Oh, well, you're a ESTP so of course you'd say that - you're always ______." It can lead people to see each other as almost different species, when really I think the best use of it is for personal growth, and for understanding that despite our different behaviors, we all may be more similar than we think.
Disgruntled people of any type have probably had bad experiences. I had a bad experience with football players in high school, so I have a certain view of them prematurely, too. It's the same thing. It doesn't mean it's fair, or that a relationship between two types can't work. And a lot of what they're disgruntled about is likely to not even happen with another INFP, or if they were healthier themselves. Despite being an INFP, INTJ, etc, everyone is still unique within those labels.
Personally, where I'm at in my life right now (transitional, insecure, feel kind of "stuck") it is difficult to be with my INTJ boyfriend sometimes. He's not a sensitive person, and he can be very blunt. He will tell you what he thinks in the interest of helping you, whether he thinks you can handle that information or not. On the one hand, this can be incredibly difficult. On the other hand, it's an opportunity for me to learn how to take things less personally, and to learn how to see criticism differently. I have always wanted to learn how to do that. It is a big weak spot in my life. So he's working on being more careful, I'm working on seeing what others say as less threatening.
Things are actually easier now at the two-year mark because I think we know more of what to expect from each other, and there aren't so many misunderstandings, there's more trust, etc. I know now that he really never means to hurt me, and that makes it easier. But I didn't measure out whether or not we would work based on our MBTI types. Sometimes it's best not really knowing what the other person sees in you - that way you can go about your life unselfconsciously, and just trust that they love you, without trying to play up certain traits in a weird, almost manipulative, scientific way.
If, however, you're just kind of down, there is a thread on the INTJ forum somewhere with some hot INFP appreciation.
So again, I would never date or not date someone based solely on what type they are. If it's working naturally, then I'd trust that. Don't force it. Try not to obsess over it, just let it happen (or not.)
My INTJ boyfriend has been great for me personally because he's so independent. We're both really similar in some of our values, interests, goals, etc, but we're also different enough to be fascinated with each other, and to have that "chemistry" people talk about. It's frustrating sometimes to feel like he doesn't understand the "people" side of things, but I think that's one of the reasons he likes me. I know he loves how intensely I love. He loves how gentle and kind I can be, but that I can also be aggressive and cynical as hell. But that's my boy, not yours. Yours may like something totally different about you.