She's most definitely cheating on him. I created an alt for this because I'm actually the other guy in a situation just like this.

Chick I became friendly with at work... I know she liked me because she would text me at random times to say "Happy Sunday" or "Goodnight" or some BS like that. She'd often mention in a roundabout way that she was attracted to me.

She was cute but she had a boyfriend so I didn't pursue.

That was until I saw dat ass at the gym. We have a gym at our workplace that I frequent. She knew I worked out a lot and just happened to workout whenever I did. God my attitude towards her did a 180 when I saw her body outside of work clothes. Before then I just treated her like a little sister. After I saw her body though, my swag was on.

I didn't get to see her a lot at work so we just worked out together. Her boyfriend would come to join her sometimes and fuck around on the ellipticals. (Free gym why not.)

He was skinnyfat and kind of clingy but other than that from what I could see he was a good dude. He knew that we were cool, but when he was around, she wouldn't let on that she knew me the way she did. I fucking loved when she would smirk, wink, or stick her tongue out at me when his back was turned.

But fuck the bro code. I'm an asshole and I love it. The first day she kissed me we were the only two in the gym at the time. I had just gone in the shower room to change. She texted me to ask if I was in there alone. Less than 5 seconds later she came bursting through the door and just threw herself in my arms. Felt her ass, her breasts and kissed for about a minute until we heard something outside the changing room.

Ever since then, we've been fucking around.

I've got so much red pill confirmation from this chick that it's not funny. Hearing how she talks about him, about how clingy he is and how she rationalizes why she is fucking around would do your head in.