It’s hard to give any advice considering the lack of any real context but I’ll try my best :)

As great as it is to want to make him happy all the time it’s not healthy for you and will effect you in the long run. You need to be as happy as you want him to be and he needs to do the same for you.

I also believe the fact that he keeps bringing it up and shows he’s clearly still hurt by this and badly, whatever you did impacts him enough for him to not let go of it. Maybe he feels you weren’t sincere, potentially trust issues and/or insecurities now.

I recommend sitting down and talking about it. Try and find mutual ground and really express how you feel about this whole situation. Living your life in guilt isn’t fair on you and for him living in a relationship in which you cant trust someone or simply just feel hurt all the time is equally as bad. Find some common ground and a way to build back up the relationship. It won’t be easy and certainty won’t happen overnight but if you believe you both love each other I know it is possible.

I’m no expert on this of course but having been in a similar position I hope you 2 can solve this and both come out as much happier and healthier people :)

Good luck!