In a world of obsessive measures and statistics, measuring emotions has eluded us (see Counting Feelings) The brain scientists show how different snapses are fired during certain feelings and thoughts - but that is a very crude way to attempt to measure a feeling. For example we know that the left part of the brain "glows" during happiness (Happiness by Richard Layard).
As a bit of humor, the Portfolio of Good Commitee of SVP Cincinnati came up with the concept of the Feel-o-meter (pronounced Fel o meter). Since the quantitative data about our Non-Profit Investees was so challenging and "flat" we wanted a way to measure the heart and not just use the head. We handed out Hershey kisses and had each Partner "vote" their ten kisses for the various Investees.
I think the reason you can't measure love is because it is infinite. The ancient Greeks had various words for love, recognizing that one word was inadequate to describe something that is infinite in nature. Try to describe how much you love someone. Ellen and I would constantly try to out do each other saying - "I love you Elephants full".... I love you a hundred Elephants full..... and so on.
And it's not about quantity. Like a wine glass - when is it "full"? Clearly not to the brim. Our love is "full" when it is just right for the moment. Something infinite that is just enough - for now. Again that is an attempt to measure love for a person for a moment in time. Does it muliply and expand around others?
In business - you get what you measure. In love - you get what you mirror.