Feelings of love may wax and wane during a relationship, but trust is constant. Infidelity is the mo

st devastating betrayal of trust a couple can experience. That survey found that when one partner had sex outside the relationship, the couple were more likely to break up. Even a little bit of infidelity can set forces in motion that eventually wrech a marriage. Only when we trust our lover to be faithful and know that he or she can trust us do we fell comfortable and at peace with our own conduct and our relationship.