That's a good question. I just wrote to him to tell him how I felt and part of it was saying that we needed to define some boundaries. We never really have sat down and said "this is acceptable," "this is not" beyond saying we would always treat one another with basic decency. To me, having your primary call up and say "I want you to come be on a date with me so I can get drunk even though you're on a date with someone else" is beyond the bounds of decency. I would not do that to my husband. He wouldn't do it to me. I don't think K would do that to his wife if she were on a scheduled date with her other partner, be it real or virtual. So why is it okay to do it to me?
It definitely is something we need to discuss.
And, if it turns out that his rule is going to be "M. can call me away at any time for any reason and I will break dates for her no matter what." then he can go have that rule with someone else, because I can't be treated that way.
I understand emergencies and that sometimes important things come up, but "I want to get drunk so you need to leave her and come to me" is not one of them.