Asked him to pull my hair and he lost his erection 😔

So let me premise this by saying my boyfriend is fantastic.

We have great sex. In the past however we have talked about how I like to be dominated sometimes and am interested in trying light bondage. I love how gentle and romantic he is by nature but he said that he could try going out of his comfort zone for me.

Well tonight I thought I’d start low stakes and ask him to pull my hair while things were pretty heated. He did..for a second...then pulled out and said that it wasn’t a turn on for him to feel like he was hurting me.

I reassured him and we cuddled for a while. I asked him what was going on in his head but he really wouldn’t circle back to the topic.

Any advice on how to approach the topic? I definitely don’t want to do anything that makes him uncomfortable but i want to understand what’s going on so it doesn’t become a sore issue.