But love is tied to your biology and evolution. Being in love with someone is a feeling, given it is a complex one. It is the chemicals in your brain which cause that feeling. As an example if you have ever been drunk you may have felt a stronger feeling of love for someone, who otherwise sober you may not have had any feeling of love for or only a smaller feeling of love for. This increased feeling of love is the chemicals in your brain getting confused by the alcohol, thus the correlation between the feeling of love and the chemicals in your brain.
Love is probably an evolved form of lust, which evolved over time as societies became more stable and humans evolved. It makes sense given the feeling of love encourages people to make sacrifices for loved ones, this in turn promotes the survival of the family, obviously giving their children and chosen partners a better chance of survival. Thus promoting their own DNA or at least their own partner selection.
Very interesting article on love, lust and evolution below.
"Love appears to be a more evolved behaviour than lust, according to new research that has mapped the brain's centres of love, lust and attachment..."
News in Science - How to tell love from lust - 13/06/2005
I'd love your thoughts on this Mike.
All this focuses on love as a "feeling" and evolved behavior for the purpose of reproduction and the continuation of the species. If we limit our view to science, I guess that's all there is but I think we're more than that.