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

This situation is orchestrated by the deliberate actions (or inaction) of the protagonist.

The heroine wouldn't willingly cheat on the protagonist, but he intentionally manipulates the situation so that she will end up raped by other men, or just flat out convinces/orders her to have sex with them. 

Either he does this for personal gain (selling his girlfriend for money or using her to obtain blackmail materials on someone), wants to push the heroine away, or he enjoys such a situation where the heroine has sex with other men.
ネトラセ 寝取らせ