What is the origin of the idiom "kiss and make up" and when to use it?

The origin of the phrase is not entirely clear, but it is believed to have originated in the 19th century in America. One theory suggests that it may have originated from the practice of actors kissing each other on stage to signify the end of a scene. Another theory suggests that it may have been inspired by the customs of boxing matches, where fighters would often embrace and kiss each other after a match as a sign of respect and reconciliation.