Cohabitation and arbitration finding

We had arbitration was over a year ago, our agreement did not allow for appeal.

My ex has a lover living in her home, her lover has no other home and all her things are in my ex’s house, they admit they sleep together much of the time, sometimes when the children are in the house, and that they have sex, her lover is at almost every activity involving my children, they exchange presents with her for all birthdays and Christmas, her lover is with her on almost every vacation or trip, including family reunions. They admitted to all of this, but the arbitrator found they were not cohabiting, and did not say why (beyond noting that an arbitrator is given broad discretion).

Given this situation, what would have to happen to bring up the issue of cohabitation again? I believe arbitration is binding even if there are errors in law. I suspect few judges or arbitrators would have found they are not cohabiting. But given the fact that an arbitrator made this decision, does this basically amount to permanent permission to cohabit without fear of consequences?

I think I could have appealed within a very brief period at the time, but it is too late - do those kinds of appeals usually stand a chance?

If the situation has changed since arbitration, you can move to modify custody based on a substantial change in circumstances if that change affects the best interests of the children.

My question was about alimony, not custody. We have joint custody, I doubt that will change.

As I understand it, cohabitation is an “absolute bar” to alimony. The situation has changed only in minor ways since the arbitration. But unless they actually get married, I’m not sure what could “change” to establish that they are cohabiting, since they already living together, having sex, presenting themselves to the public as a couple, actively involved in all of our children’s activities, spending all their holidays and vacations together, etc. Hence my question - what kind of foreseeable change could allow this question to be reconsidered? Or should I simply assume they can permanently cohabit and collect alimony?

Cohabitation is not an absolute bar to alimony, it is however a terminating factor. If the circumstances have not changed since the binding arbitration, you do not have recourse at this time.

What kinds of changes might be relevant?

A change in the circumstances regarding their living situation.