Once again, an ultimatum has never worked for you because you've never meant it.
I wish it were that simple. And there were times when I was anything but a meek about it.
About 17 years ago, we separated for a few months primarily over this issue. We didn't even speak to each other. Then things thawed and my "ultimatum" seemed to register with her. And we had sex for a while, which gradually tapered off, and then it was back to an SSM.
So, an ulimatum may seem clean and simple, but it is not. The only clean and simple option in a strategic sense is to just leave PERMANENTLY.
And I don't want to do that at this point. So if you want to say that I'm stuck because I'm not willing to leave, yeah, what could be more obvious?
