Should I talk to my boyfriend about his gaming friend?

My boyfriend (21) and I (22) have been together for 9 months. He really enjoys playing video games, and every night he dedicates 2-3 hours to gaming. Afterwards, he’s usually too tired to chat and just goes to sleep. I've been feeling a bit insecure, so I decided to look into his gaming habits. I discovered that he mostly plays with a female streamer, and it seems like they frequently team up during her streams. This made me feel quite jealous. I want to bring this up with him, but I'm unsure how to approach the topic. Part of me wants to test him to see if he’ll be honest about it, while the other part just wants to have an open conversation and express my concerns. I can't shake the feeling that there might be some flirting going on during their games. What should I do? I really need some advice!