Letting them feel me up on the bus

My girlfriend wrote to me and said she would come pick me up from work so we could go together, so I barely got out of there when she was already there, with her gym bag in hand. We took the bus and as it was rush hour, it was packed until we reached the balls. Amidst the crowd and bags, we couldn't move much, let alone in this unbearable heat on the bus. We were standing at the back but in the middle of the crowd, there wasn't even any space left and nobody budged. Suddenly, she looks at me and makes signs that someone was rubbing up against her. And she starts laughing like saying they can't be so rough. I start looking around pretending to be distracted and see an older man just behind my girlfriend. She stays still but I see how he's pushing her from behind while looking away. At that moment, my girlfriend makes signs like she's looking down and I see two fingers poking out of her leggings, rubbing against her pussy. And she makes signs that she's getting hot. The guy without any shame was touching all over my girlfriend and she, the daughter of a slut, was letting him do it. Her hand was already quite wet and I see how he starts to hug her from behind, my girlfriend trying not to look but didn't want to turn around. And I see his hand going into her leggings in front of her, straight to her pussy, and he starts to finger her, clearly showing that he's inserting his fingers without any shame. My girlfriend started to go up and down and even rubbed his ass. After a while, the guy pulls out his hand, moves away a bit, and gets off at the next stop. We stayed there for a bit longer until the bus starts to empty out and we can find a better spot, I see her with her leggings all stained with cum on her booty and in front, all wet from her own juices. And she tells me in my ear how exciting it was, asking what the guy's name was and I try to describe him. We get home and she grabs me like never before. The truth is, I want... To travel more often like that, although at the moment it gave me a bit of fear.