"I just do" is an acceptable answer. I have loved people extremely strongly (obsessively so) and not really known why. I just know that I do.

It's intellectually dishonest to give any reason if you don't know the reason. Would you have preferred he started quoting song lyrics? This guy may be a complete d*ck, I don't know. I only know what you've said in this thread and the last...

If I were reading this on any other forum, I would make the assumption that you're being very one-sided in how you're telling the story.