Is there anything else that can affect this? I have tried with two different new games, starting off with a married couple, maxed out their relationship, got them to "extremely irresistible," but then when either party tries to progress to woohoo, all of a sudden the other one's all like, "what kind of a Sim do you take me for?" and refuses to continue. No problems getting to the bed. Won't do it in the shower either. Won't do it if I get them on the bed with "extremely irresistible" mood and make them cuddle first. Still won't do it if they're in a good mood, although it's early in the game so they can't quite get to an ideal mood (of course, part of the point of woohoo is that it's fun, and puts your Sims in better moods).
Is it because the room isn't pretty enough? Is it a mood issue? Are my Sims not batting for the necessary team? (These were both same-sex couples, but they were willing enough to make out, whisper in ears, massage, etc.)
It's driving me nuts!