It sounds like your partner is ruminating on how hurt and betrayed he feels. If that’s the case, it’s important to make sure that…
- his feelings are validated
- he understands why you behaved that way
- he sees that you’re remorseful for what happened
- you’re working together to prevent such situations from happening again
- you find ways to have fun together
It’s important to demonstrate that you get how hurt he feels. Tell him that he has every right to be upset. Tell him that what you did was wrong. Tell him that you betrayed his trust and hurt him. Tell him that you’re sorry for what you did and that you regret it.
Explain to him why it happened (put some thought into why you did it). Work with him to create a plan to make sure that you change your behavior going forward. And try to highlight the positive and fun aspects of your relationship.
It’s important not to rush the process… spend a lot of time validating his feelings. The more he feels understood and sees that you’re remorseful and are trying to make amends, the less likely he is to keep ruminating on what happened.