Gottman's latest book What Makes Love Last? talks about trust and betrayal, affairs etc. I love his research and how accessible it is. Here I cite his work on the impact of loving/trusting relationships on health.
Here are some ideas "the husband's odds of dying over those twenty years (since our last research project) were eleven times higher than men in mutually cooperative relationships. They were also seven times higher compared to couples with a mixed style (meaning one partner displayed a cooperative style and the other was zero sum- treated each other like adversaries). These results are consistent with a number of studies that find men who believe their wives love them are likely to have significantly lower severity of ulcers and lower rates of coronary artery blockages and angina." (p. 228)
"When the wife's trust metric was high (even if the husband's was not) both partners had lower baseline blood velocities...wife's sense of security tends to influence the relationship dynamics more than does her husband's. When a man realizes how critical it is that he make his wife feel secure, the relationship reaps enormous benefits and so does their health....a happy relationship is good for your health. a low-trust one can be deadly...a wretched relationship is devastating to one's health, but statistics show that unremitting loneliness is even deadlier. life long isolation shortens life expectancy more than a bad marriage." pp 230-231
He continues with five detectable criteria for separating the trustworthy on pp 235-236. While it feels like common sense, it is nice to see it proven by statistics as well.
He suggests trusting others when you meet someone, but not be gullible. "If there is reason for skepticism, become wary."
All the best,