I agree that there is nothing you can do about changing your spouse’s views on the subject or controlling what they do; it is a waste of time to try. But, there are things YOU or I can do to honor this value.
1) Until I am divorced (Probably long after), I will not date. I will honor my vows, even while I am working through the divorce.
2) When I am divorced and start dating, I will NOT date or socialize with someone who is still "Technically married" but separated.
3) If I was socializing with a married friend who was having marital problems and they brought along a "Friend" of the opposite sex. I would voice my disapproval and leave. I would not socialize with them.
4) If I was talking with a friend who was justifying this behavior to me, I would explain my values and try to convince them to show respect to their spouse/marriage.
5) If I had a friend who was “Technically married”, but openly dating, I would end the friendship. Out of respect for their spouse, I would not associate with someone living like this.
In general, I would speak truth and express my values. I would not validate any arguments that try to justify this thinking.
