Spread 'em

"Yes, ma'am!", you reply, bending over the couch and reaching back to spread your butt cheeks.

"No, that won't do," Mary replies, thoughtfully. "Call me 'mistress'".

"Yes, mistress," you comply, liking where this is going.

Mary pushes a manicured finger into your ass, which feels surprisingly good. She slides it in and out a few times before adding a second one. Two is still quite comfortable, and you imagine this is she must have felt when you were inside of her. At least, you hope so. She works herself in and out of you for a few minutes, and you actually start to get hard again. With considerable effort, she manages to push a third finger between the two that are already inside you, and you realize that you had better relax or this is going to really hurt. You moan to let Mary know that you're still okay with what's happening.

Her digits leave your sphincter, and you feel the soft texture of the vibrating dildo pressing against your opening. Mary pushes forward, and the head penetrates you surprisingly easily. This actually isn't so bad!

Of course, you forgot that the strap-on isn't just girthy, but also long. When she's half way into you, she's still only as deep into you as you were into her. When she keeps going, you start to appreciate how different it is to be with a man who's actually well endowed!

Mary takes her time, slowly pushing her entire length into you in one luxurious stroke. She stops for a moment when she's all the way in, and you can feel her artificial balls pressing against your real ones. You feel well and truly full of cock. This is why you haven't been able to satisfy Kay.