A book by a founder of this site.
Intimate Relationships Create the Opportunity for Lying and Deception
As we get close to another person, we intentionally and unintentionally provide them with a great deal of information about who we are, revealing ourselves through both our words and deeds. As mentioned, creating this kind of intimacy or shared knowledge is critical, as it serves as the foundation for a lot of important rewards.
Because relationships provide so many important rewards, it should come as no surprise that people are inclined to view their romantic partners or spouses in a positive light. We place a lot of trust in our romantic partners. In fact, we think we know them better than we actually do.
But while our trust provides us with a sense of security and comfort, it also lays the ground for deceit. Research show that as we become more trusting, we also become more confident, but less accurate at determining when the truth is being told (see Levine & McCornack; McCornack & Parks).
Every study shows that lovers are terrible at telling when their partners are lying. Detecting deception with anyone is difficult to do, but lovers manage to take this failure to a spectacular low (see love is blind).
More importantly, lovers are not only terrible lie detectors, but they have a hard time acknowledging this fact. Husbands and wives like to think they can tell when the truth is being told. But, this is simply not the case. It is easier to see this type of behavior with a friend than with yourself. Have you ever noticed how a friend can be so trusting of his or her husband or wife while you have an easier time seeing what is really going on?
When we are in love, we simply become more confident, but less accurate at seeing the truth. To borrow a quote, lovers are "often wrong but rarely in doubt" (see Griffin & Tversky, 1992). This “truth-bias” or “blind faith” provides the perfect opportunity for romantic partners to engage in deception (Levine and McCornack, McCornack and Parks).
After all, who makes a better victim than someone who is eager and willing to trust everything you have to say?