Why are mandarin ducks in pairs?

In folklore, Yuanyang is a symbol of "infatuation". It is said that a pair of mandarin ducks will never be separated and will be together for life. If one of them dies unfortunately, the other will be "faithful" for life, and even die of depression. People often use the "amphibious flight" of mandarin ducks to describe the inseparable and faithful relationship between lovers. In fact, Yuanyang does not necessarily have a fixed spouse relationship at ordinary times, but only shows that kind of inseparable intimacy during the spouse period; In the late stage of reproduction, the male does not ask questions, but takes care of himself completely. The task of raising chickens is entirely borne by the females themselves. Even if one party dies, the other party will not "keep the festival", but will find another lover.