Where did those three years come from?
In the late 90s, Frederic Begbeder wrote the iconic novel Love Lives Three Years, and many people mistook this period of time for a factory expiration date. In the work, the author, on behalf of the protagonist, expresses the idea that love is the result of chemical processes that regulate hormones and neurotransmitters responsible for falling in love, sexual desire and affection. According to the hero, in such a three-year love, the life cycle is divided into three large stages: first passion, then tenderness, then disappointment and rejection, when the action of hormones stops.
According to evolutionary scientists, ancient people needed such a three-year cycle for the successful birth of children and their protection at the beginning of life. At about three years, the beginning of a relationship, the conception of a child, pregnancy and childbirth in a woman, then recovery after childbirth and supporting the child in the early stages of development fit in. During this time, parents needed to be close and support each other, and hormones strengthened this connection: dopamine and vasopressin.