I saw Sarah and Brenda...

"Liam, wait."

I walked to the bedroom. I was so afraid, so nervous, but also... So aroused. The moaning of pleasure got louder as I got closer to the door. A final moment of hesitation stopped me, but I resolved to take one more step and look inside.

Sarah was sitting on Brenda's lap, straddling her, hugging and facing each other. Their huge breasts were heavenly pressed against the other's, and they were embracing and kissing each other passionately, like lovers or wives. Sarah raised her wide hips, revealing a really thick cock coming from between Brenda's juicy legs and penetrating Sarah's soaking wet pussy. I could see the cock pulsing, shooting load after load inside my girlfriend. Then Sarah moved down again, driving her cousin's cock inside her.

"Sarah?" I uttered.

"Liam?" Sarah mumbled, breaking the kiss as she was still having an intense orgasm. She smiled and bit her lower lip. "I'm... sorry you're seeing this now."

I thought I knew Sarah. And that 'I'm sorry' felt completely dishonest. She wasn't sorry. She was enjoying it greatly. And so was Brenda, despite her completely blushing cute face.

"K-Katia! You... You were supposed to keep him b-busy!"

"Yeah, I tried, whatever."

"What's going on??" I yelled.

Sarah finally stood up, moaning as the thick futa cock slid out of her. Immediately after that, her pussy started leaking a ton of semen: Brenda had filled her so good. Was that only one load, or had she been cumming inside my girlfriend for hours?

"Liam..." My girlfriend started. She struggled, but she managed to sit up and tucked some of her hair behind her ear. "I... I guess I can't hide it anymore."

"Your cousin is fucking you! You cheated on me with your own cousin!" I said, with a tone that was more sad than angry. "How could you?"

"You have to understand! We... Brenda, Katia and I, I mean, we are... so close to each other. We've been so close since their 18th birthday party. And..."

"You mean... You've been fucking for one whole year?"

Sarah shrugged and smiled shyly.

"They've been as supportive as you all my life. I love them like I love you, even if... Even if we're related. Listen." She approached me and held my hands. I wanted to pull them away, but I couldn't. Her hands were still soft, and warm. And she smelled... Really good. Fuck. My girlfriend smelling of sex so hard was arousing me. "I love you. But this is who I am. Despite what society says. This is the love and live I choose. Please, understand. Please, choose with me and make me the happiest girl in the world."

She gently pulled me to the bed, lay on her back and spread her legs, inviting me. Her pussy was still leaking Brenda's abundant load. It was such a huge amount of jizz...

I hesitated. I wasn't going to deny that my cock was getting hard again, which is weird to happen when I've recently cum. My body and my heart wanted in so fast, but my mind kept thinking it was wrong.

"Liam." Brenda added as she hugged me. I felt the softness of her huge boobs against my arm, and the hardness and wetness of her cock against my leg. "The three of us are aware of how much Sarah loves you. That love goes beyond physical. Sex with us won't change that."

That was too idealistic. But Sarah has been showing me love all this time. She has been an amazing girlfriend, besides the incestuous futa sex, of course.

"Aaaand" Katia added, passing her arm around my neck. Being between the twins was turning me on. "You get to have sex with all of us. Isn't that neat?"

"What?"

I looked at Brenda, then at Katia, then at Sarah. Sarah had the sweetest smile on her face. She nodded slowly. I felt like crumbling, like surrendering to lust. What if things were different in the morning?