Help.. (Possible TMI)

Okay, so I need advice on giving my SO oral..

This is going to sound ridiculous..

We've been together for 2 years and I've only been able to get him off this way once in the entire 2 years..

He tells me I get super close every time but he has to stop me because he gets too sensitive.. Like to the point of pain.. I'm trying to figure out if there's a way to avoid too much contact with the head of his penis.. Or just ways that have worked for other people in similar situations..

This is something I've never had an issue with before and something I really want to do for him.