I'm not so sure that unfairness comes into the equation of "love". Surely it's about mutal giving, and to quantify that would be to dispel the premise that "love" is based upon. Besides, as Xena alluded to, love can be complex, so how DO you quantify it, if you are of such an inclination?
I would like to think that "love" is given with abandon, however there's also a cost attached to giving oneself completely, like that. How many can truly pay the price? Maybe in the short-term, where lust is involved, but the long-term?
Sadly it so often degrades into something less than "love".