Uh, what? I'm confused as to how love is related to the topic.
Well to answer your question, and trying not to sound all dorky, there is a biological explanation for love that has to do with increasing the chances of survival of the offspring (i.e, the chances are greater when there is a couple raising/protecting the child, etc.). The purpose of love was to surve this very simple function (finding a suitable mate and survival of offspring). It has evolved to be that way and in fact, many human emotions including love are shared by other social mammals, some emotions are more developed compared to other mammals and vice versa.
All emotions can be explained scientifically and serve some sort of purpose (jealously is closely linked to love, etc.).