When a gentleman tells his wive or other companion to show herself when he is negotiating to swap her for use in a group scene this is a customary presentation. After watching the wife of the gentleman she is being presented to for a swap present herself like this she just hopes he finds her both desirable and acceptable.
Couples in these scenes want to see and be seen fucking each others companions. A good performance all around can lead to long lasting friendships with extensive desired mutual benefits.
Even some benefits that involve 24/7 live in consensual adult servitude of a collared dominate and submissive relationship. More and more formerly wealthy and powerful couples are desperate to have a single man or woman or couple accept them in a consenting adult companion live in role that does not involve any employer or employee relationships. But does involve a lot of intimate sexual contact and occasional strict discipline
(Source: , via sexxgiff)