Agony Aunts: Breaking Up

It's time for the Aunts to guide you through the tumult of relationship disintegration. What are the signs that your union is going south, how can you be certain your partner's cheating on you and when do you know it's really, really over? Then there's the actual breaking up. How do you end it without being too mean? Or is being mean important? And if they break up with you, how do you keep your dignity?