That moment I realised I got turned on by watching my bf with another girl [FFM]

So once I was in high school, just turned eighteen. I was one of those nerds (which at the times still meant uncool) who had the potential to be hot (really big tits, big lips, thin legs) but still refused her potential. My bf of that time (we had already been together 3 years, he was my first and only one, same for him) was kind of like me, nice features but not a man yet.
I had a best friend at that time, let’s call her Natasha, and she was everything that I wanted to be and never hoped to: confident, amazing long hair, perfect, firm round ass, elegant, witty. I had always envied her, and at the same time found her so attractive.
I know my bf felt the same towards her. He was very religious and I was very serious too, he wanted to marry me and was sure I was the one in his life. He would never, ever cheat on me. But I saw him looking at her ass a couple of times, and once I saw a pic of her in her swimming costume saved on his phone. In that moment, when I discovered the picture, I was expecting to be furiously jealous. And I was. But I was much, much more turned on by that. And I felt so guilty about it. The thought of my ex boyfriend jerking off to her picture turned me on in a way that sex never had between us in the past. So I didn’t tell him anything.
The three of us were very closed and shared the same sense of humour. She was way sexier and more attractive than me, but I had always known that someway, she was attracted by me. I think she envied my huge tits, and when giving me “girl hugs” I could always feel her rub her tits against mine a bit longer that what those hugs required. Once, during a bet in class she had kissed me on the lips and bit my lip a little bit, and then looked at me in a weird way before shrugging it off and pretending it she was doing it for the crowd. Anyways, I used to masturbate thinking about her kisses and ass a lot, during that period, but obviously never told my bf about, cause religious and being a huge homofobic and all that kind of shit.
So one night we went to an house party, the three of us. It was in a friend’s kitchen and bedroom, we were like five and constantly going in and out the room. At a certain moment I got caught in a conversation with a classmate and I see my bf going to the bedroom. I knew that Natasha was in there, but didn’t give a lot of importance to it. The bed was positioned in a way that was almost behind the door, but you could actually see a little bit if you angle it well. After ten minutes talking with this classmate and Natasha and my bf still in the room alone (presumably in the bed area, since I couldn’t see them) I started to think it was weird. My classmate went in the garden with the others and I decided to go and see what they were doing. I get closer to the door in that angle where I could see the bed and I see the two of them “playing” on the bed. They weren’t kissing or anything like that, they were kind of wrestling but while doing that I could see my boyfriend rubbing his cock on her ass. She was pretending to fight back, but she was actually enjoying the contact. I didn’t go in. Stayed outside and watched for a while. I could imagine him, his cock hard as a rock while he was innocently pretending to “wrestle”, and I got immediately wet. Like, crazy wet, I felt almost drunk the level of excitement I had. So i go back into the kitchen and call my bf. He stands up and run towards me. I can see his dick through the jeans and I’m certain.
So we stay a while and then say goodnight. I was supposed to drive both of them back home. While we were driving back home, my bf starts making jokes about how we should have sex that night. I was shy and never talked about this stuff with Natasha, so was a bit embarrassed, but he kept joking and she kept laughing, encouraging him. So then she said “well, I could take a video” to which he immediately replies, “well, you could be in it, my gf doesn’t mind, do you?”
I was speechless. This was absurd coming from him and left me without words. So I didnt say anything. He was the one deciding things for the both of us most of the times, I didn’t have a very strong personality.
So I was driving, he was sitting behind and she was sitting next to me. She goes behind with him and smiles at me. She puts an arm around his shoulder. Still, I was speechless. I was very jealous and actually a bit angry they were so insolent. But also, I could feel my pussy getting wet. So he says “[my name] come here”, like he’s talking to a dog or something, and I do that, still confused. He says “suck it a little bit” and I started sucking him but it wouldn’t get hard, like maybe the situation was too much for him. So I suck for a little but it’s still soft and I think I’m doing something wrong. Then it immediately gets hard, I look up and Natasha has just started kissing him in a slutty way. When she stopped kissing him his cock would soft, so I went up and started kissing him. Then she went down at him, and while she was sucking him he was moaning so much I couldn’t kiss him, so I just kind of stayed there looking at him, moaning and mumbling her name. So after a while he pushes my head down and we start sucking him in two, I lick the balls and she licks the top. He can’t hold it anymore, and comes in Natasha’s mouth.
We all stat quiet for a bit, and that’s when my bf suggest Natasha should kiss me to see “how it feels”. Natasha agrees and I don’t reply, so she starts kissing me, biting my lips and sucking them a bit. My panties are soaked. My bf suggests we take away are shirts and adjusts the seats so we can lie down. I feel my nipple rubbing against her small this while she kisses me, so I grab her ass. My bf has taken his cock out of the trousers and stroking it. He keeps giving us orders with a rough voice I had never heard. He says: “you should do a 69 now”. Natasha takes off her pants without any hesitation, my bf looks at me impatiently so I do it too. I’m lying down and she puts her pussy right in front of my mouth. I’d never seen (literally) a pussy that wet. It was dripping. I started kind of awkwardly slurping her clit while what she was doing with mine felt amazing. I could also see my bf jerking off and repeating “oh, good girls, like this, good girls” until he came and squirted on her ass. I came but felt so shy I tried not to show it. I don’t know about her.
After this we went home, and I never knew if they fucked again behind my back, after that night. At this point I think that’s very likely.
Anyways, that was the moment I realised I was a “cuckquean”: the thought of my bf cheating on me in front of me was a huge turn on. Still is.

Source: reddit.com/r/gonewildstories/comments/a6kvqc/that_moment_i_realised_i_got_turned_on_by