I may be reading to much into it but I think Irma called Ilonas bluff at the end of the bath. Ilona was fine playing with Irmas tits but when Irma sat back down and went to, what looked like, suck one of Ilonas boobs, she couldn't get out of the bathtub quick enough. One final ass grab on the way out and Ilona poofed into thin air.