I would say it's the blonde one looking back, she can't seem to be able to wait a single extra second to kneel before a stud and suck his cum to the last drop, otherwise, she wouldn't be pushing the other girl to move forward.
The sissy is in the background. His wife has just looked over her shoulder and can see the size of the 'present' their Master has for them. The wife knows what's coming. The sissy is going to be surprised.