What is love?Watch
it was the man that created "civilised" love. if it was down to instinct and nature everyone would be sleeping around as much as possible.
And also biology can't explain why someone would fall in love with someone they know they can't have, but love anyway. And someone would love another person so much that as long as the other person is happy, they are happy, even if that person doesn't love them.
Love is more than just a feeling, or lust. Love is what makes the world go round, what holds people together, what makes life worth living. It is the most beautiful thing in the world and can also be the saddest.
Heh, I'm so romantic
To the contrary, I'm of the opinion biology is as good an explanation as any for the problems you pose. It is 'instinctive' logic, based ultimately in genetics that allows people to have non-sensical love. It doesn't have the rationality of logic, forsight, etc; merely some evolutionary 'memory' of the semblance of what constitutes an appropriate relationship.
Also because 'love' as we define it has 2 related manifestations with probably similar origins but different purposes. Love, as in social familiarity leads to dependence on social interaction, as in essence people are conditioned to desire happiness, provided by 'love' and thus by social interaction. The other of course is the subject of all too many songs and poems. Therefore I'd imagine it would be possible for the two to be associated and so for the former to lead to the latter, or the latter to the former independent of the sensibility of such transitions.
Love is fricken pain in the buttocks to be honest! and OMG how incredibly dirty does that sound I certainly didn't mean it like that.