Too Idealistic - INFPs often take their idealism too far, setting themselves up for disappointment as, again and again, evil things happen in the world. This is true on a personal level too, as INFPs may not just idealize their partners, but idolize them, forgetting that no one is perfect.
Too Altruistic - INFPs sometimes see themselves as selfish, but only because they want to give so much more than they are able to. This becomes a self-fulfilling prophecy, as they try to push themselves to commit to a chosen cause or person, forgetting to take care of the needs of others in their lives, and especially themselves.
Impractical - When something captures INFPs' imagination, they can neglect practical matters like day-to-day maintenance and simple pleasures. Sometimes people with the INFP personality type will take this asceticism so far as to neglect eating and drinking as they pursue their passion or cause.
Dislike Dealing With Data - INFPs are often so focused on the big picture that they forget the forest is made of individual trees. INFPs are in tune with emotions and morality, and when the facts and data contradict their ideals, it can be a real challenge for them.
Take Things Personally - INFPs often take challenges and criticisms personally, rather than as inspiration to reassess their positions. Avoiding conflict as much as possible, INFPs will put a great deal of time and energy into trying to align their principles and the criticisms into a middle ground that satisfies everybody.
Difficult to Get to Know - INFPs are private, reserved and self-conscious. This makes them notoriously difficult to really get to know, and their need for these qualities contributes to the guilt they often feel for not giving more of themselves to those they care about.