Unlike child support, spousal support is often very difficult (if not impossible) to modify after the divorce is final, so getting it right the first time is a must!
This is my problem with non-modifiable support awards. Life happens, and then what? In CA, the court is required to consider many factors, with co-habitation being one of them. Plus, the court retains jurisdiction over marriages of long term; meaning either party can return to the court to ask for a change of order based on a change in circumstances. I say, file a motion to have the order changed. What's the worst that could happen? The judge says no, then you'd be right where you are now anyway.