Kivana wasn't a cheater, but when she walks in on her fiancè with her sister. Her fiancè thinks she's forgiven him and they have moved past it. Little did he know she was plotting the sweetest revenge.
Naruto got betrayed by Hinata, she was having an affair with Shino. Unexpectedly he would've expected Kiba but no it was Shino. He wants nothing more than revenge but that wasn't his style. Shikamaru knew what the blond was going through so he dedicated himself to making the blond smile again. By any means necessary.