I think I have figured out why mother nature makes us fall in love prevalently when we are young. As we get older people change. They get more quirky. But that's not the reason why.
The reason why is that we are wiser and notice other people's quirks more. We are capable of recognizing the ones that are dangerous, and the ones that define others as obsessive compulsive, manic depressive or what ever other disorder.
It gets harder and harder to find a long lasting partner as we get older because of just that, we notice their faults more than we did when we were younger.
When you're young and reckless you don't pay attention to details as much, to faults and quirks. When you're older it's often all you notice in a person, the things that annoy you, or just plain piss you off.
What do you think?