Agree upon trusting one another. Once you have taken your promise, don't do anything to break that trust. You have both taken vows to be faithful in every way to one another. Now it's time to believe in one another and trust your partner. Suspicion and doubt don't cause a spouse to cheat, but if one spouse exhibits high degrees of any of these to the other, it spells trouble for the relationship. Set reasonable boundaries and stay within them - this fosters trust, and the longer you each stay within the boundaries you have agreed on, the more trust you will build as time goes on.