The girl's boyfriend has a best friend that is a girl and spends too much time with her, giving her too much attention, and she is at the spot where she can't say anything or show jealousy since they are "just friends".
A guy marries a girl to make her a prop in his life, so people won't be suspicious that he is having an affair with his married secretary.
The person who cheated left for someone else and came back out of guilt. They did everything to try and fix it, but they realized the other person just wanted to take revenge for the past.
This is a love triangle story among three people: a guy has to decide between a girl and a guy. In the end, they decided to live together to see who the man would choose.
A married couple both have affairs, but are unwilling to choose to leave or not.
Someone who loves someone and does everything for that person, but that person does the same for another person.
A girl gets pregnant after having an affair, but her child doesn't look like her husband. The husband doesn't know.