Lets say your really close friend, or step sibling, or sibling dated someone. They break up after one year of being exclusive. Years go by, and you hook up with that friend or siblings ex. Or, flip it. You date someone for 12 months, break up, and years go by, and a close family, or friend of yours hooks up with your ex. How common is this? Does this bother you, or create a rift in the relatiknship with your close friend or family? What happens if all three of you are in the same room? Awkward?