I'm a bit confused. So your boyfriend actively talks about all of the groupies he's banging on the road?
And you're okay with this? Both the fact that he's banging groupies on the road AND that he talks about it. The thing you are worried about is him telling everybody he has a girlfriend?
If all of that is right, then my guess is you are worried that the blogs will judge you for sticking with a man who is actively spending more time inside women than tampons. Which I can understand. And you're right, its hard to ignore blogs and tabloids when your name is all over them. Your boyfriend, famous as he is, has probably learned to develop a thick skin. You have never had to since he kept your lives private. I think that you are fair to feel how you do, but I think famous people like to stay famous and putting their business out there is part of the gig. I think you need to explain to him why you don't want that to be the case, but prepare yourself for it anyway.
And then like he said, you're going to have develop a thick skin and try not to pay attention to it. That's your best best.