Recently, a friend and I were discussing the challenge of how to stay friends after a breakup. She was caught between the time-honored dilemma of thinking it was the adult thing to do and wondering what the point of it would be. Well, I’ve heard you, friend, and I’m here to help. This week’s Illustrated Guide offers some helpful tips for trudging through a long, slow, pointless impersonation of congeniality with someone you used to love.