The first episode of a new podcast called PsychCrunch features interviews with researchers in the field of personal attraction. While they are pitching it toward people looking for help with dating, the information could also be useful for anyone writing a romance or romantic comedy screenplay or novel.
The guests include researchers from the University of Pennsylvania, University of Baltimore, and Rochester University. Here's the link:
http://digest.bps.org.uk/2015/02/episode-one.html
There's additional interesting and useful information on their collection of articles for this year's Valentine's Day: