is my bf cheating?

my (27F) bf (30M) has this co worker i have never met before that he constantly plays online mobile games with. i have never met the co-worker but am aware of her existence as this was a topic i have brought up before with him. she’s the woman my bf told me not to worry about.

this coworker would constantly comment a be the first person to like my bf’s social media posts and my bf would blow me off to play games with her among other things. his co-workers would often tease them as if they were in a relationship and it bothers me a lot. i told him that it would make me feel better if he limits contact with her in his personal time. he told me he would but…

i found out from one of his friends that while they were away on a trip (him and his group of friends), he would step out, go online and talk to this girl in game but would keep it hush hush and sounded pretty intimate. i asked my bf to introduce me to her and if i could join them on one of their night outs but he would constantly get mad about it and shoot me down, saying he doesn’t need to do that because i shouldn’t interfere in his work life and that our relationship should be separate from that.

im not 100% sure where to go from here as we don’t live together. do you think he’s cheating on me?

TL;DR my(27F) bf (30M) has a female worker he told me not to worry about but he constantly gives her attention even though it has made me uncomfortable.