I am, to some degree, avoidant. I'm not afraid to confront difficult issues or people, but sometimes it is just plain easier to avoid them.
If I have difficult decisions to make, skipping of the whole decision-making part can happen occasionally. I focus more on issues that I can be solve immediately, and I let the more difficult decicions develop in my mind for a week or two... or longer. That's avoiding.
Also, it is said that INFJ is perhaps the most social type of introverts, but they're still introverts... which creates almost a contradicting complex: to be with others and to be alone. It surfaces so that INFJs go to others when they feel like it, but they don't let others come to them at will. It might be hard to get into contact with them, but it's easy for them to contact others. For example: I don't always answer my phone, but I make calls myself when I feel like it.
Also, when everything else has been tried, as the last solution to people problems the INFJ doorslams the difficult person out of his/her life. Either for a period of time or for good. That too is avoidance. However, we are really patient and enduring and we do our best to fix that kind of issues... but sometimes that's just not quite enough.
Obviously this doesn't apply to all INFJs. I'm writing on how the INFJ stuff I've read applies to me.