Well, even if she said YES I WANT TO DO IT, our beta MC is gonna say: how if we are both girls? while showing his pussy. (I know you all know what I mean with this. Of course girls can do it between themselves).
Sadly MC is gonna keep making yame so mad at him that she will initiate the NTR on him and he will not even know why she did it since he is even denser than the densest of the chemical elements.
But on the off chance he decides to show that he actually is a man....
1) he gets cockblocked by call from hotel saying time is up or call form x friend of any of them asking stupid shit.(most likely)
2) he gets cockblocked by yame falling asleep (not likely)
3) he cockblocks himself because doing it in a love hotel is not romantic and special, and since he wants it to be it then he says no.(cliche)
4) unreal bad luck happens! Some sort of catastrophe happens at the hotel and they have to leave immediately right at the moment they were gonna have fun.(plot demand of many mangas)