Karen puts a stop to it

(Thanks to Dack for suggesting this route)

Decisions, decisions. Matt looked from Eliza on the bed to his naked Mom standing in front of them. Both women were super-sexy. Eliza glowed from a thin sheen of sweat. His mom seemed almost ready to fight Amy's mom to protect her offspring and to have her own chance at his cock. Over time he hoped he could do both. But right now he could only do one.

"Not happening, mom." Karen interrupted before he could get his thoughts in order.

"What?"

"You had your chance. You could have done him last night but you were too proud of your puritanical inhibitions. You could have been the one to take his virginity but you turned him down and made Amy call her mom to handle the responsibility that should have been yours. So there's no way you're going to butt in there and take the pleasure she's earned. Matt, you can worry about mom later. Right now there's an attractive MILF lying on the bed with your dick in her hand and she wants you. Take her. Own her. Make her yours by pounding her pussy until she squirts all over all of us."

Eliza grinned. "I like the way you think, girlfriend."

Mom shook her head. "But--"

"What part of blowing your chance don't you understand, mom? If you want him tonight, and if he's not mad at you for turning him down, we'll see. Right now you have two choices. Sit quietly and masturbate while your son drives Eliza to orgasm or leave the room and masturbate in the laundry room. Which one is it going to be."

"I... I'll stay here."

"Good. And don't think I'm not going to remember the way you talked back. A good girl obeys her mistress."

"But--"

"Obey!"

"Yes, mistress.

Matt turned back to Eliza. "Shall we continue, sweetie?"

"Hell, yeah!"