Hey Gil,
I am fascinated by the love-drug idea.
The following drug-information is drawn from my lay-man's brain to me, so I could be wrong!
The cognitive enhancement pill for love is in illegal circulation already, and comes in two flavors! The first is ecstasy, which produces a strong urge to bond with others, facilitated by a very low threshold for bonding (i.e. no need for courtship). The second is heroin which produces a strongly bonded feeling (with or without other bodies present) during the crescendo of the 'high', and as one comes down from the high, they feel tremendous grief, as if they've lost a strongly bonded partner (or object).
As an Evolutionary Psychologist, I've been exposed to massive amounts of information that has led me to a pseudo-conclusion on the nature of love and bonding: it's hard work worth doing, and the less work we invest in these bonds, the less we reap. So, I agree! A pill which elevates feelings of love would lead to relational (cultural?) lethargy, where our behaviors (motivated by a lack of love) to pursue the things that bring love to us (interesting careers and hobbies, ecstasy and heroin) fail to activate, leaving us contently snuggling on the couch while we starve to death; too in love to move. Just look at heroin addicts.
-Zack