One of the reasons why we crave love, and seek it so desperately, is that love is the only cure for loneliness, shame and sorrow. But some feelings sink so deep into the heart that only loneliness can help you find them again. Some truths abt yourself are so painful that only shame can help you live with them. And some things are just so sad that only your soul can do the crying for you.
If we really crave for love, it's because the nature force us to look for the partner and have children. Programmed reproduction is the only reason for which we cannot bear our loneliness.