Triangle Relationship is best

With the new year starting at vocational school, i was finally being able to continue my education.
When i entered the classroom, i immediately spotted Carolina, one of my closest friends. We greeted each other and spoke about what happened during our summers when suddenly, two people that i hadn't seen before met my eyes:

One being a short, stereotypical nerdy girl, wearing glasses and pigtails. She had beautiful black hair and a huge ass, which seems to slightly bounce with every step she took.
The other girl next to her was a very sporty looking, brunette tomboy with a massive rack that could barely be contained by her top. She was also one head taller than me, towering over the shorter girl.

"Oh, i see that you have noticed our new classmates.", said Carolina. "Our neighbour class they were in got dissolved because of too little pupils so now they're here, the short one is named Rebecca and the other is named Alex. You should go and introduce yourself!"
Hesitantly i walked over and introduced myself to the newcomers. We all found out quickly that we had similar interest and agreed to sit together in class.

Over the coming weeks we grew closer and became friends: We went to see movies, went to gym, played video games together and geniuly had a good time.
Over the time I slowly developed a crush on Rebecca since she seemed to "click" with me especially, which had me acting more shy around her.

Since Alex had successfully gotten both me and Rebecca into sports we regularly met at her extensive home gym, placed in her garage. One random tuesday, it being our regular workout day, i arrived at Alex House, seeing her already warming up. "Sorry i'm late, traffic was a nightmare, where's Rebecca?", i asked.
"She said she had to prepare something and would join later, but since you're already late she should be here shortly, why don't you help me warm up already?", replied Alex.

"I would prefer it if he would help me warm up instead.", a smug, familiar voice said. I turned around and one of the most marvelous sights met my eyes. Standing in front of me was Rebecca, wearing the most skin tight clothing i had ever seen:
Her fat ass was wobbling around in her shorts and her small B cup breasts were fitting perfectly in her sports bra, with the nipples clearly visible through the fabric.

I was flustered and tried to not let her notice but she just looked at me with a mischievous smile. Alex didn't seem to react to the situation at all, excusing herself to go to the bathroom.

When she had left, Rebecca asked me to help her do stretches, telling me she wanted to try new poses, which i reluctantly accepted. Normally Alex would always help her stretch so it seemed odd that she wanted my help.
All the poses we did together seemed suggestive, with some them looking like they could be straight out of Kamasutra. During the final pose i was on the floor with her over me, her round bubblebutt starting to bulge out of her shorts. Suddenly Rebecca acted like she slipped, making a cute little noise and landing her fat rear right on my head.
Her ass was completely enveloping my face. I could feel it's warmth and softness through her shorts.

After a few seconds she got up and apologized, saying she slipped and asking if i was hurt. But i was already starting to get aroused which she immediately noticed and her mischievous smile returned. My face became red and started apologized but Rebecca shut me up. "Its ok.", she said. "I've noticed how you act around me, i know that you have a crush on me. I already suspected it but Carolina told me yesterday by accident." I became even more embarrassed but suddenly Rebecca grabbed my growing erection and started stroking it. "And you know what? I have the same feelings for you. So why don't we take this to the next level?"

I was too flustered to say anything but she just pressed her lips on mine, giving me a sloppy kiss. Our tongues met and we started making out. Grabbing a pack of condoms out of her gym bag, she pulled down my gym shorts and rolled a one over my cock. I removed my shoes, socks aswell as my shirt and watched in awe as this beautiful, young women was undressing in front of me. Her cute, little B cups sprang free, finally being released from their prison.

When she pulled down her pants, she slowed down, knowing how much excitement was building up inside of me.
Eventually her thicc buns got revealed in all their glory, Rebecca took my hand and laid it on her left asscheek. It felt soft yet firm. She said: "I know how much you like my fat bubble butt, i've seen your eyes wonder under my skirt a few times already. Now why don't you lay down and let me do the work."

"But what about Alex?", i asked. Lining my dick up with her shaved, already wet pussy, Rebecca replied : "Don't worry about her, i locked the door when you weren't looking, she won't disrupt us. Now let's do this!"
With a swift motion, she sat down, making her vagina swallow my whole dick in one go. She was incredibly tight, even through the condom i could feel every detail of her fleshy walls. They were twitching around, almost if trying to milk me.

What followed was the most pelvis destroying sex ever:
Rebecca quickly moved up and down, her massive dumptruck slamming against my hips. "OH BABY YES", she exclaimed, accompanied by loud moans.

After about 10 Minutes i could feel myself getting close. "Rebecca, i'm...", i cried out. "Yes i'm close aswell, let's do it together, OH FUCK.", she replied. Her movements started getting even faster, her massive ass basically hitting me like a battering ram, until the breaking point was reached.

We both orgasmed with excessive force. Now her pussy really was milking my cock.
I came as hard as i have never came before in my lifetime. Once the final spurt had left me, Rebecca leaned in and kissed me. I pulled my dick with the condom on out her and we started cuddling in the wonderful afterglow, truly feeling each others love.

Suddenly we heard a knock on the door and quickly got our clothes back on, hiding the condom in my gym bag. We went to the door, unlocked and opened it. Standing on the other side was Alex with her hands on her hips.
"Why was the door locked and why are you guys so sweaty?", she asked.

Rebecca replied: "Oh i must have accidentally locked it, we were just at the peak of our intense workout. I'm sorry that we started without you. Now let's return to training, shouldn't we?"
"Fine by me.", Alex said.

What we didn't know was that she had witnessed the entire thing through the keyhole from other side of the door, her panties wet from the show we gave her.