A lot of people have been romantically in love with somebody who they feel wasn't appropriate to marry.

I don’t think we’re an animal that was built to be happy; we are an animal that was built to reproduce.

Barriers tend to intensify romance. It's called the 'Romeo and Juliet effect.' I call it 'frustration attraction.'

Women apparently are quite drawn to men who have differences rather than similarities in their histocompatibility system. They pick it up by smell, and they can pick it up from kissing.

You size up someone physically in less than one second - too tall, too short, too fat, too thin, too old, too young, too stuffy, too scruffy.

A woman of 40 or 50 or 60 can take estrogen replacements, get facelifts, spend her money in bars.

Research shows that couples who have a lot of similarities, including intellectual compatibility, end up staying together.