My (20M) girlfriend (20F) is playful in her talks with guys, and continues to make friends with them against her own suggestions

My girlfriend is quite oblivious to others flirting with her. As we were getting together, she had a particular guy she has previously flirted with do the same in her comments across social medias, and she replied in a playful manner – at this point we were exclusive, not together.

I took this onboard, told her I was uncomfortable and felt disrespected, and she slowly cut connection. Although, it took another instance of me bringing it up for her to completely stop, as she didn’t notice it was playful, and then she recognised it and pulled off.

This has happened with the occasional guy, she is stunning, and gets more compliments than I could hope for, and that’s very reassuring, but her playfulness comes down to social media use and the normalisation of it.

I’m generally more reserved, however equal to her in this relationship in all regards, so I figured I was fairly logical in my thought process.

Nevertheless, she had a coworker she never spoke with prior to us talking. She mentioned a few times the thought of me making friends with other girls after our relationship began was generally unneeded unless it was a work thing, which I agreed with. More recently, this guy has become her work ‘best friend’ as they often work the same shift.

They don’t plan to hang out outside of work, however he recently went through a breakup and she is the one that consoles him throughout it, and randomly brings it up to me, which does bug me at times. They do by chance end up at the club together, she goes with her girl friends, and he’s been there on two occasions and he has driven her home (with his mates, girls and guys in the car), which was something I was uncomfortable with, but she communicated this and I’d rather her home safe than complain in the moment.

They seem to be playful as well in how they talk to each other from what I’ve seen, i.e him toying with her, and she tells him to ‘stopppp.’ I’ve told her on two different occasions about this, and have just been looking at this situation, I don’t intend to control and say stop, I’d rather have second opinions on whether I’m irrational in thinking this is a shitty situation, one I shouldn’t be put into.

TLDR: Girlfriend has a new work best friend who he vents to, she consoles him, though it’s just a texting and in workplace basis. She also has been to the club with him (unplanned), but I trust nothing was done as I trust her friends to tell me. They have been playful in their texts before from what I’ve seen, and she has a past of being playful while we were exclusive. She also suggested we should not make friends of the other gender, specifically best friends. Am I rational in wanting something done about this?

I’d love some perspective on this situation, ways I should tackle this, and whether I’m just picking at nothing. I’m fairly secure in myself generally speaking, this just reminds me of a previous situation a fair bit so I’d rather prepare myself more than anything.