When you see an animal that is hurt, do you feel sorry for it? Do you try to help it? Or do you pelt it with stones? Harming an innocent animal may not even occur to most of us, and yet there are people (and kids) who take pride in causing such harm. Maybe it shows some false sense of being in control?
How abnout removing stones on the path to prevent some bare feet from getting hurt? Or to remove a nail from the road to prevent a tyre puncture? This is all nothing but being sensitive, being attuned to the needs of others, as the great Jiddu Krishnamurthy would say.
This set of feelings for those around us, is not coming because these other people are ours, but because we are aware of the divinity and beauty inside everything.
Love is being sensitive to others. Doing things for others, irrespective of what others may do back, no different from what a mother does for her baby. When the heart is filled with love and affection, it becomes happy. And this happiness itself is nothing but God.
Love = happiness = God