Trust is essential in a marriage or romantic relationship.
It is impossible to have a close, intimate relationship when people do not trust their partners. Trust involves knowing that a partner has your best interest at heart. It is hard to feel safe and secure when you are involved with someone who would betray your trust (see, rebuilding trust).
Not only is trust important, but it also influences our deceptive behavior.
People have a fundamental need to "get even" - it is called "reciprocity."
And reciprocity, or "tit-for-tat," is one of the most studied aspects of our human nature (see, Axelrod and Hamilton, Cosmides and Tooby, Gouldner).
We like to treat people as we have been treated. Smile at someone and watch what happens back. This desire to reciprocate - the desire to return favors and repay punishments is very difficult to control.
So when a partner betrays our trust, it's natural to want to get even. Essentially people think "if you are not honest with me, why should I be honest with you?"
And reciprocity helps explain why trust is so important in a relationship or marriage. If you do not trust someone, who you are close to, you are less inclined to tell the truth (see, Cole).
Deception can quickly take over a relationship when trusting is missing.
