This American Life had a fascinating show on marriage a couple weeks back (and have made an audio stream available). Most interesting was an interview (in act one) with Dr. John Gottman, a researcher who videotapes & bio-monitors couples discussing something they disagree about and codes their heart rates, expressions and how they speak to each other. From about 15 minutes of data he has an 85% chance of predicting if the marriage will last the next 4 years and whether they’ll be happy with it. If he records another hour or so of the couples talking about how they met & things they share, his success rate goes up to 94%.