Never happened. If I want to he somehow can always tell immediately without me ever doing or saying a thing. Usually though, if there's a lot going on & he's exhausted, all I have to do to get his attention is hike up my skirt when I bend over and it works everytime. He says do you want me to lick your... ha ha.
Have you asked him why the hell he isn't wanting to? If you haven't already, try pretending you forgot a towel or something while in the shower & run out of the restroom and in front of him while you "look" for the towel or a pair of underwear anything will work. I'd say that should definitely get him going! If not then I would say WTF? Do you know how many men would give anything for the ladies to want sex with them this much? That should remind him how lucky he is.