Agony Uncles: Breaking up

And it was all going so well. But now it's time for the Uncles to hold out a strong hand and guide you through the agony of a relationship that is going quickly south. What are the signs that it's deteriorating, how can you be certain your partner's cheating on you and when is a union beyond resuscitation? Then there's the actual breaking up. How do you do pull the pin without being too much of a prick? And if they break up with you, how do you keep your dignity? No one said this was easy.