Maybe because she thinks your dick is too big bro. But the reason is irrelevant anyway.
A WL can withdraw consent at any time and doesn't have to give you a reason and once she says no that's it it's over.
You fact that you have already paid money means nothing.
All you can do is walk out and ask for your money back from reception.
There is no point arguing with the girl. And of course if you try to force her it's sexual assault.
So you did the right thing to just stay calm and walk out.