Try grinding your way through, like just grope her breast through clothes a couple nights in a row to lower her sensibility.
Also if you wait she slowly falls back to sleep there is some sort of indicator ring around the action button.
Actually dev gave an even better tip lower. Just wait a couple nights before rushing her. Apparently it does the trick.
General tip, look if the info you're looking for has not been given already before asking questions. Quite often if someone struggles with something he/she might not be the first one to do so. So FAQs and whatnot, or in this case previous comments. If you don't do it for the devs/mods, then do it for yourself, your answer was already there 4 days ago after all, right when you wanted it.
Also, assuming you're on computer, on webpages such as this one F3 allows quick search for key words.
Done with the lecture. Have fun peeps.