I’ve been a fan of John Gottman and his research into what makes relationships tick since someone first thrust a battered copy of his book, “Seven Principles for Making Marriage Work” into my hands aeons ago (look it up on Amazon; it’s worth owning). His clear identification of what creates toxic relationships and how successful repair attempts help counter and even mend that toxicity, are seminal influences in a lot of relationship psychotherapy in the late 20th and 21st centuries.
This article provides a handy introduction to the principles he has witnessed time and time again in almost 30 years of observing couples in his “Love Lab”, and provides some solidly-scientific basis for the kinds of changes we therapists often work to introduce into clients who are in relational distress. And find a copy of his “Seven Principles”; it really is worth the investment of time to read.