The traditional modality of a relationship entails the promise to be faithful and sexually exclusive to a single partner for the duration of the relationship.
The clandestine nature of swinging and the swinger's lifestyle community seems to have created an etiquette that all but expunges the possibility for violence or acrimonious conflict.
"To swingers, physical acts of sexual pleasure with someone you respect, just for pleasure, and making love to one's lifetime partner are two distinctly different things".
This form of sexual identity is clearly outside the norm, and pushes the envelope as to what most 'normal' couples would consider acceptable.
The concept of monogamous relationships has been inexorably tied to the institution of marriage between couples (as well as that of relationships in the 'commitment' phase).
It is noteworthy however that monogamy is required for neither of the above, rather, it is society that assumes that the former cannot exist without the latter.