Hmm, I would consider the options. Does he ever come into your room unannounced? Does he knock on the door and call your name? Does he play videogames or watch sports and yell at the TV? Basically, why does he need to know? If it were me, I'd have his girlfriend explain the situation to him. That way it's not super awkward for you.
I'm not saying that it definitely will get awkward, but here's my experience: I was dating a guy with 3 roommates. Boyfriend loved that I was a camgirl. Told his roommates. They were all bro-fisty about it (Wow, that's so cool, dude!) with him, but never said anything weird to me besides "Oh, I guess YOU can buy the beer tonight since you're making all that dough!" But when I got comfortable with the fact that they all knew, I would occasionally comment about camming. Just things like, "Well, I've gotta leave early since I'm working tonight." And after I started being cool with talking about it, the roommates started perving on me. And would say things about my body later. It was just extremely awkward, to the point to where I didn't even talk about camming anymore.
Now, that's just my experience. Yours could be totally different. But if it were me, I'd ask his girlfriend to tell him to hush during the day/night, and to just text you if he needs something during those hours.