The Good Old Relationship Contract

  This trope is so common in kdramas especially. It's generally used as a contrivance to keep an otherwise unlikely pair together for some reason and allow them some "fake" skinship, while acting as an obstacle and still allowing the possibility of a third (or fourth) party to interfere with our OTP.

"Taking Responsibility"

  A common theme in dramas, it can refer to something as simple as paying for dry cleaning or damages to property. More commonly, it refers to a lifelong commitment to marriage after getting someone pregnant (or sometimes after a one-night stand).