People have always been ostracized for adultery, royalty or no. You need only look at stories from e.g. the Old Testament or similar to see how long this has been a thing in human society.
Infidelity is as old as the institution of marriage. Very few people are ever ostracized for it, and most of those were women. Among elites, it was usually expected to have lower-status women for fun and not to bother the nobly-bred wife for anything other than bearing legitimate heirs.
Infidelity is as old as the institution of marriage. Very few people are ever ostracized for it, and most of those were women. Among elites, it was usually expected to have lower-status women for fun and not to bother the nobly-bred wife for anything other than bearing legitimate heirs.