I hated my mom on all those pills.
Is it possible that you have pushed this so often that she thinks that you can only get off while seeing or thinking of her with other guys? Since then my wife has mention it again a few times, and finally I told her I would do it, bluffing of course, since I know her friend is such a straight person and she'd never go for it.
I know no ones to blame and no one did anything wrong per se.