The diagnostic questions here include everything that’s important to pay attention to in deciding whether to stay or leave. If it’s not in the questions, it’s not so important in deciding what’s best for you, and you can let go of worrying about it. So let’s get started.

You’ve probably put a lot of energy into thinking about the bad times in your iffy relationship, but in this first step I’d like you to think about the good times for a moment. The best time, in fact. Try to remember when you felt most comfortable, most satisfied, most optimistic about the relationship you’re in. It could have been the day you met, the time you took your first trip together, a special rainy weekend the first year you were married, a period when you were working together to achieve some joint goal. If you’ve been together a long time, don’t worry about being too thorough. Trust your unconscious to throw a searchlight on a “best” time even if it’s not the absolute best.

Now ask yourself: 

Diagnostic question #1.Think about that time when things between you and your partner were at their best. Looking back, would you now say that things were really very good between you then? 

This is a simple question. Were things between you actually very good when they were at their best?

What do I mean by “very good”? Some people, even in relationships that feel awful now, know that there was a time in the past when things were wonderful. They were in love, they were genuinely happy, they felt good about themselves when they were with the other—there was a kind of happy magic of warmth and connectedness. Their answer to question #1 is yes.

But other people realize that the “best” was never very good. Something was wrong. They’re usually referring to an empty, distant, tainted, painful quality at the core of their relationship, even back then. Their answer to question #1 is no.