Oh, my. So you think science can't deal with the "soft stuff", huh? Well, just check out Alteration of the platelet serotonin transporter in romantic love, bucko! Here's just a little hint at what's waiting for you:

BACKGROUND: The evolutionary consequences of love are so important that there must be some long-established biological process regulating it. Recent findings suggest that the serotonin (5-HT) transporter might be linked to both neuroticism and sexual behaviour as well as to obsessive-compulsive disorder (OCD). The similarities between an overvalued idea, such as that typical of subjects in the early phase of a love relationship, and obsession, prompted us to explore the possibility that the two conditions might share alterations at the level of the 5-HT transporter.