Nyx makes Cassie eat her out

"Dont you dare stop fucking her." Nyx commands, while positioning herself in front of Cassie. She opens her legs, but her skirt blocks your sight, you can´t see her pussy.
Nyx slightly lifts Cassies head, and looks her in the eyes. "I think you know what to do. Be a good girl."
Then, she pushes your girlfriends head down between her legs.

You dont directly see Cassie eating Nyx´s pussy, you only see her head bobbing up and down, and Nyx moan quietly.
All this time, you kept the same pace, now Nyx looks at you. "Go faster."
You obey, although hesitantly. Not because you have any issue obeying her, your way past that point already, but because even without any real stimulation to your dick, you feel an orgasm building. You cant tell which aspect it was that did it for you-the humiliation, seeing your girlfriend like this, Nyx´s behavior, everything that just happened-but you´re afraid to cum soon if this goes on much longer.

Nyx now forces Cassies head down with her hand, you hear her moan. Nyx looks at you. "You enjoy seeing your girlfriend like this? Handcuffed, head burried between my legs, her pussy getting stretched out by a strap-on bigger than you?"
You´re not sure at first if she actually expects a response, but she doesnt continue speaking, so you decide to answer.

"Yes misstress, I enjoy the sight of my girlfriend submitting to you."

Nyx smiles. "I bet you do. Getting exited by now? I bet you wish you could pull out that strap-on and really fuck your girlfriend. For a couple of seconds at least, before you would cum anyway. But it least it would be in her."

You feel your dick twitch at the thought.

"But you´re not gonna get that chance a lot anymore if you submit to me. If youd ecide to continue this after tonight, you´re gonna have to earn the right to fuck each other."

You wonder how Nyx would enforce this, but you decide not to question her. You have other worries anyway. You feel yourself reaching the edge and from Cassies movements you feel like that she´s close as well. Nyx doesnt seem like she would tell you to stop anytime soon though.