All introverts share a common need: time spent alone in order to recharge, reflect, and decompress. So deep is the need in the INFP and INFJ that if neglected, they begin to experience lethargy—a fogging of the mind, if you will.
Of course, with personalities so complex as the INFP and INFJ nothing is ever simple. For them, seclusion is a need of peak importance. Unfortunately, so is a need for deep and meaningful relationships. They are often torn between needing to spend time alone, while simultaneously wishing they could be with a friend or loved one.
The Introverted Idealists desire closeness with a select few, usually one at a time. Unless they are completely recharged, large groups produce too much stimuli for them, and their personalities are keen to pick up nuances, often flooding them with information to the point where they feel overwhelmed.
But time spent with one person, exploring their personality and letting themselves be explored is particularly special to them. In fact, it is a need just as great as that for time spent unaccompanied. Often enough, they feel a powerful sense of guilt over not being with another person, or, as confusing as it may sound, they might even feel lonely when they finally do take a time-out from people.
Read more: http://mbtipopculture.wordpress.com/2014/05/16/infp-and-infj-being-alone-together/