Activity partners get into conflicts many times because one's ignoring function is the other's weak Polr. One partner expects the other to protect and not disturb their Polr, as their dual would. However, an activity partner is not cut out to care about the other's Polr function, and when they misuse it they do not understand why it hurts the other so strongly.
For example, an ISTp may get angry and lash out violently, not paying attention to thier use of Se. The INFj flinches from the violence and recoils from that person. Whereas if it were an ENFp they would understand the misuse of Se and take care of it accordingly. The INFj just get's disgusted and scared of uncontrolled Se. This is why their dual is more careful with using it.Ignoring Function
The ignoring function is also called the observing, or limiting function. A person has very little use of this element, as it is the rival image of the base function, representing an antithetical approach to the same domain. It lies in the subconscious as a persistent annoyance to the individual. Therefore, he or she tries to ignore it. When lectured by another on the use of the ignoring function, the individual sees it as superfluous information, for he or she knows how to use the function well, but chooses not to use it in favor of his or her more convenient base function. Usually the base function creates byproducts relating to the ignoring function, but the way it describes such information is very carefully chosen to fit the view of the leading function.A person limits the expression of this element in public (in favor of the base function), but sometimes uses it extensively in private, and can call upon it when necessary. For example, an SEI usually defaults to his base function and shies from activities that are highly physical or cause conflict, but if inevitable confrontation arises, he is able to use his Se and become fiercely coercive and quarrelsome for short periods of time.The extreme avoidance of this function can make it appear weak at times. However, when engaged it does not cause the same kind of psychological stress as a weak function, instead creating a kind of boredom or malaise.- See more at: http://www.sociotype.com/socionics/f....l0W0HVXo.dpuf
Also, an INFj may ignore Fe and this hurts ISTp because they need people to be extra careful around their feelings due to Fe Polr, which their dual gladly does.