A "plot" twist, ugh...
I would call it a fun (if not exactly surprising) twist, but with the "relationship" progressing that fast (and with a side-order of sudden sexual harassment, welcome or not?), what could have been the vehicle for just about any sort of interesting character interaction is instead just a skank kink story.
Not that those don't have their place, but... Eh. Reading this just makes me feel kind of grimy (nothing to do with the cross-dressing).