I don't know about him, but for me, and I imagine for most men, we don't really need "a connection" to get hard. That's usually what women require, but men are simpler than that. LOL.
We are turned on visually, tactiley, or our by our thinking, etc.
If a woman is sexually attractive, it usually doesn't matter if we even know her.
It could be caused by many things, but I doubt that it's lack of a connection.
Maybe he doesn't know why either.
Sometimes it's medical or psychological.
It could be many reasons.
if you fit into his concept of what turns him on physically, then i doubt that he wouldn't be able to have an erection because you aren't the ideal partner for a successful relationship.