Biological Instinct

Love is just an illusion of the brain; for sexually reproducing organisms, the essence of love boils down to a single thing: females willingly surrender their reproductive capacity, while males willingly surrender their survival capacity.

It's simply that women bear children, and men earn money to support their wives and kids.

How do you tell if someone loves another person? By whether they are willing to have children for them, willing to spend money on them, and willing to sacrifice their own abilities and value.