Some recent events have caused me to consider the topic of forgiveness. Forgiveness is one of those things that you can't demand; like love, respect, and honor. I've come up with the idea that being forgiven is not a moment in time. Not a milestone, but a process.
The idea is that if you can be in the process of being forgivable and asking for forgiveness, then the person you offended can be in the process of forgiving you. If you stop the process, then the person you offended can also stop the process.
This allows the person you offended to set a reasonable boundary that prevents you from continuing to offend. Until you start acting forgivable again.
The forgiveness process also involves a sincere, heartfelt, apology. This is critical to the process, because it requires you to acknowledge that you did something wrong. Next, a promise to make every effort to avoid re-offending in the same way is necessary. Then, asking for forgiveness by physically, verbally, making the request completes a part of the process.
Finally, looking at being forgiven as a process, rather than as a moment in time, cuts short the idea that once the person you offended "forgives" you, you are off the hook and the subject will not, or should never, be brought up again. It just doesn't work that way. If you continue to offend in similar ways, then all the previous offenses will be brought to mind and the accumulation of them will be brought to bear.
I see no contradiction with Matthew 18 in this approach. In fact, I see it as very consistent with the slave falling prostrate and begging for patience. That speaks to a heartfelt commitment to a process.