Wouldn't this depend upon his love language preferences? Personally, I'm into physical touch and words of affirmation. That's not necessarily an INFJ specific thing though. *shrug*
As far as being concerned about you after deep conversations, well, that's Fe kicking in. The deeper a conversation is, the more personal it is, and the more likely one is to be hurt or upset due to differing opinions or whatever else. Speaking for myself, I'm not fond of even unintentionally hurting those I care deeply about.
So when I might disagree with them on something, I want them to know I still value their opinion and that I don't put them in a negative light for having a different one. And I'm also aware that at times my Ti will get the better of me during those conversations and I might come off as more assertive (read: argumentative) than I intend to. Because, like I said, these deeper conversations can be personal as well, and I'm not immune to it anymore so than the person I'm speaking with is.
Anyway, to put it more simply, verbal communication isn't really our greatest proficiency. Sometimes, we just like to make sure we haven't overstepped our bounds, because we care. It's like a bad dancer who's out on the floor with you and just wants to make sure he hasn't stepped on your toes yet, or if he has, that you're able to forgive him. ;o)