How did love originate?
“There are in the end three things that last: faith, hope, and love, and the greatest of these is love.” (Corinthians 1:13)
Faith, hope, and love (charity) are the theological virtues.
According to the Catholic Catechism, a virtue is an habitual and firm disposition to do the good. It allows the person not only to perform good acts, but to give the best of himself. The virtuous person tends toward the good with all his sensory and spiritual powers; he pursues the good and chooses it in concrete actions.
From the above I infer that the virtue we call love is the working of Actual Grace, the special gift given by God to assist us in performing specific good acts.
An act of love resulting from and with the awareness of Actual Grace is always rewarded with the feeling of joy. Therefore, the origin of love is Actual Grace.
In a like manner, the origin of Hope is Sanctifying (or Habitual) Grace and the origin of Faith is Sacramental Grace.
I have found the efficacy of Actual Grace in the “joy of giving” .
Yppop