Love has different definitions in different times. The modern definition is that two people, based on certain material conditions and common life ideals, can form the most sincere admiration for each other in their own hearts, produce and live together, and long for each other to become their lifelong partners.
When you fall in love, the chemicals in your brain are called monoamines, including dopamine, phenylethylamine, serotonin and norepinephrine.
In ancient matriarchal society and ancient paternal society, love has another experience, which is not simple monogamy. With the development of society, love is also developing in the direction of civilization.