Many year ago I had a heated debate about what love was and because it seemed impossible to define, did it even exist? I can't remember the outcome of the discussion and I still can't define what love actually is but this quote from Captain Corelli's Mandolin comes closest to my own personal belief about love :
You have to work out whether your roots have so entwined together that it is inconceivable that you should ever part.
Because this is what love is.
Love is not breathlessness, it is not excitement, it is not the promulgation of eternal passion. That is just being "in love" which any fool can do.
Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident.
Those that truly love, have roots that grow towards each other underground, and when all the pretty blossom have fallen from their branches, they find that they are one tree and not two.