I found a lot of value in this book. The whole "School of Life" corpus has so far been very useful, thought-provoking, and short but dense reads. This one is no different.
It has a ton of great ideas and lessons on what relationships should be, what its purposes are, what our feelings and what certain dynamics tell us about us, the other, and the relationship...
It can help you determine what your personal needs are, what you want in love and life, how to be a better partner, how to set healthy boundaries and much more.
It does discuss the idea of "when to stay vs when to leave", but it turns out there isn't a lot to say on the subject, and there isn't a ready-made solution that will 100% apply to your situation and tell you whether you should in fact, stay or leave. It tells of hints, not signs. It offers suggestions, not rules. And to be fair I'm not surprised about this, it's just that I think we all would like more clarity when making such painful decisions.