Paul Zak, the guy who showed that oxytocin affects all sorts of positive human emotions, as well inventing the field of neuroeconomics, posted five tests you can use to discover whether a man is likely to stay faithful.
The tests illuminate the relationship between oxytocin, vasopressin and testosterone. If that recipe isn't just right, a man's more likely to be a seed-scatterer than a bacon-bringing-homer.
They're smart, science-based, and most of them you can do yourself without the need for lab tests. I covered his post in the blog I write at LifeGoesStrong.com, and I'm afraid that, in what is certainly recursive but necessary in this link-crazy world, I am cycling you through that in order to read his post. Is that too, too awful?