Come home to a lovely girlfriend!

Sarah and Zoe were chatting gleefully when I got to the apartment. I think Sarah was laying her head on Zoe's thick, juicy thighs, but she quickly stood up to receive me with a hug. She had taken a shower and smelled of flowers. Her huge breasts pressing against me really felt like home.

"Liam! Oh, last night was incredible! Although it was tiring to be up all night, I totally loved it!"

I was so happy for her! She was wearing a pleated skirt, and a tight top with straps. Zoe seemed as shy as usual, she was wearing a cute dress, although it was a bit shorter than usual, revealing more than half of her amazing thighs.

"We've made dinner." Zoe said with a timid smile "We've already had it, so have as much as you want."

I sure did that! While I was eating, Sarah sat on top of Zoe, who was sitting on the sofa, not straddling her like other times, but giving her her back. Kinda like reverse cowgirl position (I felt weird to think about sex positions when describing my girlfriend). I didn't look at them much at the beginning, but it seemed Zoe was adjusting her position. Zoe's skirt had pulled up a bit, but Sarah's skirt was long enough to cover everything. Regardless, there was a big length of skin where their thighs were touching. I tried not to stare at that point much.

"Alright, Zoe!" She said. Her breath had become a little heavier suddenly, but her smile was growing wider. "Today we'll do that exercise I mentioned before! We need to strengthen your core and hips, ok?"

"Yes. Thank you."

"Normally we'd need some weights, but since we have none, my own weight would do. You have to... Ah... You have to put some effort on your feet and abdomen so you can lift your hips, and thus lift me."

A good part of Sarah's future job would have to do with rehabilitation and care, so I felt proud when she started doing those exercises to alleviate Zoe's extra muscle condition.

Zoe started moving her hips upward, slowly but surely lifting Sarah. She seemed to be applying a lot of **** on her legs to keep a constant upwards motion. I was already having dinner, but I couldn't help but look at them. Sarah's face was of concentration, and she was blushing hard. She was probably focusing on balancing her weight on her girlfriend's body.

"Are you ok, Sarah?"

"Y-yes, Liam. I'm fine." She gazed into my eyes as if she were falling in love again. "We're... We're moving forward. Zoe's muscles are so... Strong and... Hard at times that they need extra stimulation. Do you... Do you mind we do this in front of you?"

I looked at the for a second. Zoe had slid her hands under Sarah's top, and was fondling her breasts as they jiggled with every rhythmic thrust.

"Yes, baby, use them as support..." Sarah said to Zoe, but then quickly spoke to me again. "So? Liam?"

"Yes! I mean, no, I don't mind. It's your nurse duty, and I think it's so cool you want to take things further with Zoe to help her deal with her condition."

"Really? I can take things further?"

"Sure!"

"I love you, Liam! Come here!"

I stood up from the table, went to her and gave her a brief kiss on the lips as she bounced on top of Zoe. As I went back to continue eating, I couldn't help but to be amazed at Zoe's strength. She was lifting Sarah just with hip thrusts rather easily, and she was doing it faster, too. Her legs were not only sexy and thick, they were powerful!

When I finished having dinner, Sarah was blushing intensely, and Zoe was thrusting upward so hard, if it weren't because she had my girlfriend by her breasts and waist, Sarah would've been bouncing up several inches.

"Woah, you're much stronger than you look, Zoe!" I admitted as I was doing the dishes.

"Thank you, Liam" She said, breathing heavily, focused on lifting. "Your girlfriend has helped me exercise so much. She's so good at this."

"Ah, she'll be the best nurse! I'll go take a shower before bed, alright?"

"Yes, Liam! I love you!!" Sarah spoke kinda loudly.

"How...? Uhm... How long does this exercise take?"

"As much as... Oh, goddess, as much as Zoe needs...!"

"I'm almost there. Don't worry about us, Liam. Go take a shower."

I nodded and I went to the bathroom. As I turned on the shower and got in, I heard them. Zoe had increased the speed of her thrusts much more, and Sarah seemed to be getting off balance, because she started moaning and sighing with a lovely high pitch. I hadn't noticed, but there had been a weird wet sound before, now it was just more evident. Then I understood what it was:

It was the friction of their thighs! Of course! Sarah had started to get sweaty because of the exercise, so the friction of her bare legs against Zoe's made that weird splooshing sound. Yeah, definitely.

I also noticed I had gotten hard. The visuals of their thighs rubbing together was delightfully burned into my mind. So, hoping not to make much noise, I reached down and started jerking off, picturing those sets of thighs rubbing against each other, while their owners kissed. I could hear them in the living room still. Sarah was being a bit louder, maybe giving Zoe instructions about the exercise? I couldn't hear much, as I was concentrating on my cock. As I climaxed, Sarah let out a loud sigh, and I imagined she was climaxing too. Good lord, what was I doing? I was imagining my own girlfriend having an orgasm, basically scissoring her friend, while at the same time I was shooting my load in the shower. Regret and guilt became present soon after.

When I got out of the shower, the girls weren't there anymore. The door to their bedroom... Our bedroom, I mean opened a little and Sarah's face appeared.

"Liam! We're going to hit the bed early today. Is that alright? I'm just so sleepy."

"Uh... Sure, no problem. Good night, Sarah!"

"Good night!"

"Good night, Liam!" Zoe's sweet voice came from some point behind Sarah, then the door closed.

I lay on the couch once more, wondering how they'd feel if they knew I was masturbating while they were doing nothing but innocent, helpful exercise.