A situation very similar to this is why we started cuck/cheating. It happened with my friends BF. He didn't have a licence at the time and I had offered before anything ever happened to drive him to work and back most days. We talked, he was normal and sometimes funny if a bit shy at times.
My friend was quite open about her sex life, and always talked about her better experiences with different guys.
This guy was kinda new, about 2 months in to their relationship. But my friend was already talking this guy up more than the others before. Which of course peaked my curiosity, and after asking if he was just that good my messenger app went off. I opened the app only to find a photo of a cock bigger than I'd ever seen or had. My friend saw the look on my face smiled and said "and he lasts a long time too!"

About a week later it became kinda obvious that my friends BF knew I'd seen the PHOTO. I'm also sure he'd seen me looking at his pants, which would be why he assumed that maybe I wanted him or atleast his cock. Which I was in awe of obviously, being huge compared to my partner, but never thought to actually see it in person let alone touch. I had seen some of my BF's friends dicks briefly before, but those guys were just streaking or playing around and were average in size like my BF.

But when he pulled it out in the car in front of me, I struggled to keep my hands to myself. I think I struggled atleast at first because I fooled around in the car with my BF all the time, and was maybe just second nature. But after the initial shock of what was happening, I just started giggling.

He asked if I liked as much in person, and if I wanted to touch. Of course at the time I said no, I took him home and went home myself. Needless to say quite wet, very nervous, feeling guilty but very wet.

More happened, eventually..
Photo by Supashare with the username @Supashare,  March 7, 2021 at 5:19 AM. The post is about the topic Erotic Infidelities and the text says 'A situation very similar to this is why we started cuck/cheating. It happened with my friends BF. He didn't have a licence at the time and I had offered before anything ever happened to drive him to work and back most days. We talked, he was normal and..'