Yes

You decide not to think about it. Alyssa won't have sex with Sid. You know it, she wouldn't betray you. Besides, your dad needs you right now, so you have to leave for a week.

So, knowing that Alyssa will be spending an entire week alone with Sid, you pack your things and leave to go help your dad.

After the long flight, you call Alyssa from the airport. She doesn't pick up, she must be busy studying or something...

When you get to your dad's place, you call again. After quite a few rings, you are worried she's not going to pick up again. After about ten more rings, she finally picks up.

Alyssa: "Uhm...hey babe..." She sounds out of breath.

You: "Hey babe, I just got in to dad's place. How are you? I tried calling earlier, you alright?"

Alyssa: "Yeah! Yeah....I'm fine...thanks babe...uhh...glad you got in safe.... Sorry I didn't pick up earlier...I was in the shower..."

You: "...with Sid...?"

Alyssa: "uh, yeah...we wanted to get clean for tonight's lesson."

You: "oh.... okay..."

Alyssa: "Sid taught me about....edging..."

You: "What?"

Alyssa: "It's where we bring each other to the edge of orgasm....only to deny it to us at the very...end... we've been doing it all day.... we're both...sooo...horny... we've been naked all...day..."

You: "I....what...I don't know what to say..."

Alyssa: "Don't worry babe....I won't cheat on you..."

You: "W...what are you... doing now?"

At that moment, you hear a rustling. Now Sid is on the phone.

Sid: "Hey, bud. Hope you don't mind...ugh...I've got my cock up to her....belly button, and I'm about to come so....fucking....hard."

The butterflies in your stomach go crazy. Did he say up to her bellybutton or up on her bellybutton, like they're grinding, or maybe he's jerking himself off...?

You: "uh...oh...okay...."

Sid: "You don't mind if I....cum...right where my cock is now....fuck... do you?"

You: "Uh...your cock is on her bellybutton...?"

Sid: "Yeah....fuck... something like that..."

He's come on her before like that, so you guess it's no big deal to do it again.

You: "You did it before....so I guess it's okay..."

Sid: "Thaaaat's a good....boy....hear that, Alyssa? Matt says it's okay for me to cum...right...here..."

Alyssa in the background: "Thank....you....babe!"

Sid: "She'll call you....later...." Then he hangs up, and you pull down your pants and jerk off to some old pictures of Alyssa. You wish so many of them didn't have Sid's cock or cum on them as well as Alyssa's beautiful body. You finally cum to a picture of Alyssa on her knees, squeezing her large breasts together for you. A gorgeous sight a bit undermined by Sid's dirty cum covering her tits...

The next morning, you wake up to a text. It's from Alyssa. When you open it you see it's a picture of Alyssa, naked. Her large tits sandwiching Sid's massive erect cock, which stands up through to her mouth. She's smiling at the camera, apparently pleased with her first tit job. The caption followed: "Your sexy girlfriend just woke me up like this....man, you're a lucky guy..."

Yet, you're not the one receiving a tit job from her, so far she hasn't done anything sexual to you...frustrated, you set the phone down and take a shower, unable to stop imagining Alyssa coaxing the cum out of Sid's balls with her soft, creamy tits....

Alyssa doesn't call, probably too busy edging Sid along....so you go on with your day. Your dad needs your help, after all.

As it turns out, your dad needed help with his boat, so you go with him to the marina. The boat is in a sorry state, it needs a lot of sanding and painting.

Dad: "Thanks a lot for coming over to help, Matt. All your other siblings said they were too busy."

You weren't really aware no was an option, you would have much more preferred to keep an eye on Sid and Alyssa, while they finish their lessons...

You: "Sure, dad. Happy to help..."

After a while of silent sanding, your dad speaks up.

Dad: "So...what's new with you, son? Haven't heard from you in a while..."

You: "Uh, yeah. Sorry, I've been...busy...I actually got a girlfriend..."

Dad: "That's great news! I'm happy for you...why didn't you bring her over?"

You stop sanding, pondering if you should tell your dad about what your new girlfriend is doing with Sid the homeless stranger with the big cock you found on the street.

You: "Uhm...yeah, no she's busy with...her studies..." Too embarrassed to tell your dad your girlfriend is studying sexual things with Sid. Sucking his cock, showering with him, giving him tit jobs...who knows what else. The only thing keeping you sane is knowing that sex is off limits for them.

Dad: "Oh, sure...do you have a picture? I'd love to see her."

You pick up your phone, and flip through the pictures of Alyssa. As you do, you slowly realize you don't really have many photos of Alyssa where she isn't naked, with Sid's cock, his cum in her mouth, or covered in his cum. Finally you find a selfie of you both, before you met Sid. That was a happier time.

Dad: "She's gorgeous, Matt! I'm so happy for you" he says as he gives you a hug.

You: "Thanks dad, her name is Alyssa, and she's a virgin, too."

Dad: "You haven't had sex with her yet? How long have you been dating?

You: "A few months now...Alyssa is very... precious about it...and nervous..."

Dad: "huh...well maybe she's saving herself for marriage...maybe you're the right guy for that, huh?"

You: "Heh...maybe..I don't know, dad. She's, Uhm... Actually seeing a...sex therapist for that..."

Dad: "A what? Sex therapist? I didn't know that was a thing...what does she do for Alyssa...?"

You: "He, actually....Sid. He's increasing her confidence in her body... sexually...so she stops being so shy towards me...so maybe I can take her virginity. So...Sid is giving Alyssa some lessons."

Dad: "Lessons...? What kind of lessons, like... lectures?"

You: "Uhm...no...she's practicing...sucking his cock, and stuff...."

Dad: "W..what did you say? Your beautiful girlfriend sucked that guy off?"

You: "uh...yeah, many times now actually. And they've showered together, he's shaved her ...down there....and made her orgasm with his mouth...and..."

Dad: "I..I don't want to hear any more....and you're okay with this?"

You: "Uhm, not really. But it has improved my relationship with Alyssa. She's definitely not shy anymore."

Dad: "uh, yeah. No doubt if she sucked that guy's cock in front of you...if you don't like it, why don't you stop them?"

You: "I've tried, it doesn't work. Alyssa likes it and Sid convinces me everytime that this is actually a good thing..."

Dad: "Well, I can call them right now and put a stop to this. Alright?"