That's why "I could be persuaded" works. She doesn't have to get too verbal and throw herself completely out of the sexy mindset she's trying to build up, but he still gets a pretty unambiguous statement.
Of course somewhere in there he'll have to really get that coming on to his wife, even if she's not up for it that particular time, isn't going to upset or offend her, and she's not going to "put out" just for his benefit and then resent it.
a fine and enviable madness, this delusion that all questions have answers, and nothing is beyond the reach of a strong left arm.