What is love?

I always turn to shakespeare for this question: Though I'm not sure I can remember his words perfectly... Here is a rough outline Love is not love that falters when it alteration finds, Or bends with the remover to remove, Oh No, It is an ever stead fast mark That Looks on Tempests and is never Shaken It is the star to every wandering bark (ship) Who's worth's unknown, Although its height be taken. Love is not times fool, though rosey lips and cheeks may fade. Love alters not with times brief hours and years Though within its bending sickles compass come but bears it out even to the edge of doom. If this be error and upon me proved I never wrote, nor no man ever loved.