My gf's husband had a problem with self-control in sexual situations for a good long while. This eventually almost led to the dissolution of their marriage, which is when he finally woke up and committed to changing.
He let her set the rules and pace going forward. They withdrew from outside encounters completely for a while, then went back in with guidelines (no bdsm activities with other women without getting an explicit ok from her, for example) just for him since he was the one with the problem. He still occasionally messed up, in which case she would yank back on the leash, so to speak, and revoke his outside contact privileges for a period of time to show him what his lack of control would get him.
It all sounds a little messed up, like she was "training" him, but it was coming from a place of love, desire to figure out a way forward, and acknowledgment of difficult to fix but impossible to live with issues on his end. Things have since gotten MUCH better now, to the point that he still checks in with her but she trusts him to do pretty much whatever because he's proven himself and really reformed.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.