Cranky asked me to stop by and give my take, soooo...
OrangeAppled has some strong insights into how the INFP works. However, as she noted they are generalized but I do believe that they address some of the more obvious traits.
My post is going to be more personal and give you a clear idea of how an INFP mind works.
I am an idealist and a romantic. I never really know how I'm going to react to someone or how far I'll go until I get there. I often find where people draw their personal boundaries before I've found mine. The key to this is I will generally give what I feel is a little more to the relationship (not necessarily romantic) than I am getting which in turn tends to make the other person give more back. This continues until one person has reached their boundaries of what they are willing to give. This can and will go up and down as things develop and people find out more about one another and the situations we find ourselves in.
The intensity of the relationship will often dictate how important it is to me, so it means that it needs consistency of some sort to continue or to grow. Cranky can attest that after almost 12 years of not seeing each other, we picked up pretty much where we left off. I have had people come into and out of my life and back into it almost my entire life and it's never been different. I miss those who have taken different paths or have passed, most of them a great deal but I will not chase them. If I were to turn away, it would be a very difficult thing to do and the last thing I would want is to be chased.
I could go on trying to explain the spider's web of feelings that influence my decisions in how I interact with people
More to the point and answer the question is this:
How do we do it? We have a deep affinity for people. I mean look at the letters in our type, it screams of our ability to feel, sense feelings, learn and observe. I'm not saying every INFP is the same (I'll address that in a different post). However, the ability tends to be natural and takes time and effort to understand...Like any skillset. This tends to make us seem very friendly, compassionate and kind. This can be seen as a weakness obviously, but it can also make us desireable as well. Does it make it less real? Less true? No, the INFP feels everything, and if anything is not honest about it, it is generally that they are not being honest with themselves about what they might want...instead they believe that what is given freely doesn't come with a price, or expectation beyond treating others like they want to be treated.
As to why he did it, you can take what you will from what I wrote above as to that. I cannot say what he may have been feeling since I don't know the gentleman well enough. Did he act out of character for INFP? From what I've learned, he did not.
Honestly it seems like it was a problem in communication, and that falls to both of you to find a way that suits both of your styles if you are unable to 'cross over' to the other's method of communication.