Don't hurt me...no more...
I'm glad that I'm not the only one who now has this stuck in their head. Than's alot NHAH!
There are a few different types of love, but they're all just biochemical and neurological effects that were developed over the 3.5 billion years of evolution. Species (typically social mamals) that developed chemical responses that lead them to take care of their offspring, protect other members of the group, etc. are all more likely to survive as a group. Even if love drives someone to protect a member of the group that is not their direct decendent, they're still protecting a possessor of the genetic makeup that predisposes a person to love (in most cases, anyway) so this genetic predispostion made members of the group more likely to survive to pass on their genes.
Love, and indeed all emotion, is a distortion of your thought that is "designed" by evolution to cause you to behave in a manner that is more likely to cause your genetic makeup to survive indefinitely.