Things were going great for a few months, but then on that fateful night the hinge of the cupboard broke and all of a sudden you were sitting there on your chair in full view of Marc. He took it quite well that evening, but said that he really had to think about our relationship.
The next morning he called me and explained that you viewing us during sex did not bother him too much. He mentioned he had seen your teenie weenie and kind of felt sorry for you and understood you enjoying a real man fucking your wife.
However, you masturbating while we had sex was bothering him. So he said that he would only continue our relationship if you would be prevented from masturbating.
He immediately mentioned that the best way to do that was by fitting you with a chastity belt while we were having sex. And until then you were not allowed in the house while Marc and I had sex.