I feel like I’ve answered this before…
The two of you need to have a talk about this (in a non-sexual setting), because the intensity of the emotional reaction he’s having is not normal and it seems to me that something else might be going on.
As with any serious relationship conversation, don’t use blame language, do your best to avoid hurting his feelings, but be firm and clear and encourage him to be honest.
Ask him if there’s anything you could do to make it easier/better for him, and remind him that non-penetrative sexual activities are just fine with you (assuming they are just fine with you!).
It also might not be a bad idea to suggest that he see his doctor (or to suggest that the two of you go to his doctor together), just incase it’s an issue with his testosterone or his physiology or something.