Well, I'll probably get laughed at, but love appears to be a chemical reaction in the brain. How mere chemistry and matter could produce emotions and consciousness, I have no idea, nor does anyone else. But this appears to be the case. It also seems true that the love we have for others - a mother's love for her children - exist only because they were selected for by blind mechanical processes.
You are in good company if you find this to be a chilling prospect. Nobel-prize winning physicist Steven Weinberg wrote,
"Worse, the worldview of science is rather chilling. Not only do we not find any point to life laid out for us in nature, no objective basis for our moral principles, no correspondence between what we think is the moral law and the laws of nature, of the sort imagined by philosophers from Anaximander and Plato to Emerson. We even learn that the emotions that we most treasure, our love for our wives and husbands and children, are made possible by chemical processes in our brains that are what they are as a result of natural selection acting on chance mutations over millions of years. And yet we must not sink into nihilism or stifle our emotions. At our best we live on a knife-edge, between wishful thinking on one hand and, on the other, despair."