These morphine-like opiates calm and reassure with intimacy, dependability, warmth, and shared experiences. Not as exciting or as stressful as PEA, but steadier and more addictive.

The longer two people have been married, the more likely it is that they'll stay married. In part, they become addicted to the endorphins and marital serenity.

It is the absence of endorphins that make long-time partners yearn for each other when apart. Absent endorphins also play a part in grief from the death of a spouse. According to Mark Goulston, M.D., professor of psychiatry at the University of California at Los Angeles,


"Adrenaline-based love is all about ourselves, we like being in love. With endorphins, we like loving."