Q. I've become really good friends with my best mate's boyfriend, but last month she cheated on him. She's not going to tell him, and I can't as I've been friends with her for so much longer, but I feel guilty each time I see him. What should I do?

A. It's not fair of your friend to put you in this situation, but she probably figures that your loyalties are strongest to her. No one outside a relationship can know quite what's going on between a couple, and telling her bloke what happened might cost you both of their friendships. Tell her how awkward things are and that you hope she doesn't make a habit of it. If it's a one-off, you should let it go for the sake of friendship, but if it keeps happening maybe it's time to broaden your social circle and focus on other friends. Or alternatively ask her not to tell you any part of her behaviour. What you don't know can't torment you, and being unable to brag about her conquests to you will drive her potty.