Here’s the scene: One of your colleagues is a married guy. You both play on a recreational sports team. One day after a game, he asks you back to his hotel for a drink. (He commutes to work from another city.) He makes clear that he wants to have sex with you, but you don’t want to have sex with him. What do you do? (a) tell him no, and leave? Or (b) join him on the bed, say nothing and hand him a condom?