One of the things we used to talk a lot about around here is the emotional connection the WAS still has with the LBS. Of course, it's vice versa, as well.
We don't just suddenly fall out of love or detach. It's a choice and an activity.
So while those emotions are still there, there is conflicting emotions. Roller coaster. Emotional outbursts. Often, the LBS will get the emotion in the form of anger.
When that connection is no longer there, then we are simply relating to a friend or acquaintance and that really carries very little stress. There is indifference or apathy, then the emotional connection is gone.