"Open Relationships: Back Door Exit From Commitment?"

 Relationships between couples usually define exclusive commitment between two people. "Open" relationships, or swinging, a practice of swapping partners between couples for sex seems contradictory to the rules of standard commitment, but many "committed" couples are indulging in these practices and believe that there are "rules" to these practices that still keep their commitment intact. Is an open relationship or swinging healthy to couples, or is this practice merely a form of consensual infidelity?