Strangely, I am the same way. However, I am slowly beginning to understand why and how it works. I too lost a long dear friendship, and I could have cared less. Howver, what I realized later is I wasn't in the relationship, but rather another part. I found myself in tears for what I thought was for no reason or out of the blue. I learned it was this part that was mourning it. Yet I had no idea. I think of the person and feel nothing. But I know it would not be true of this other part.
I am as one would say the out personality and I don't feel emotions much like you mentioned I can laugh or feel what I call very basic emotion. But I have no connection to anything. But T says its protection. It is what it is... Not sure I would say cold.