By the deliberate actions/inactions of the protagonist, or by the agreement with the significant other, in this VN their committed partner ends up engaging in sexual relations with other people. Only protagonist's significant other (whether they are male or female) has sex with others. Under normal circumstances neither side of the couple has a desire to cheat, but due to the desires of the protagonist, their significant other will end up having sex with other people. This can be a mutually agreed act with a trustworthy person, which the partner convinces their significant other to have sex with, or a selfish act, with the partner selling or whoring their significant other for personal gain (money, blackmail material on someone, etc.). In every case, the protagonist is (at least initially) fine with their significant other being sexually involved with other people, and possibly even enjoys it. Don't confuse with Swinging where both romantic partners have sex with others, or Polyamory, which is a long time agreement involving romantic feelings, while Netorase is a momentary satisfaction of a kink.