Searching for a cheating uke (6 posts, 5836 views) Posted: 1489d 4h, 37m ago by pookaloo in Yaoi/Yuri
It's been a while but I believe Rules and its side stories + prequels have a lot of cheating involved between the couples.
Also, definitely read Double Call. It has all the stuff you're looking for.
EDIT: BTW the cheating is only part of an arc and won't c ...