“If you don’t have faith in your partner, you take the stance that he or she should change so that you can maximize your own payoffs. Likewise, your partner wants to change your behavior for his or her own selfish reasons. When distrust abounds, neither of you includes the other’s well-being in your calculations.
“Turn this description of distrust around, and you have my definition of its opposite. Trust…is the specific state that exists when you are both willing to change your own behavior to benefit your partner. The more trust exists in a relationship, the more you look out for each other…it doesn’t mean that [you] always put the other’s needs ahead of your own – that is unlikely to be healthy. But it does mean that [your] happiness will be interconnected.”
excerpt from What Makes Love Last? by John Gottman, Ph.D.