netorase

A fetish involving one of the party of the lovers intentionally manipulating the situation so that their partner will end up raped by the third party, or just flat out convinces/orders her to have sex with them against their will.

Not to be confused with the similarly worded, "Netorare (寝取られ, also NTR)."

If both parties consent to have the third party involved, use swinging (relationship) instead. If the party who is having sexual relationship with the third party consent without their partner's acknowledgement, uses cheating (relationship) instead.