no, it’s valid if you don’t want to and it’s valid that he wants you to the fact that he wants you to is pretty cool. He trust you to do that. It’s amazing that he felt comfortable to actually let you know that but the fact that you don’t want to do it is also very much OKbecause it’s your mouth. So just tell him no and buy him a toy.
I was the one who asked my partners if I could, 1 paused but gave it a try and loved it, 1 was hesitant and thought about it a few months before he became obsessed with it, and 1 said nah I said okay and we swiftly moved onto a different topic. If ur bf gets upset or tries to guilt trip you for saying no or tries to immediately coerce u those are red flags. It’s an intimate thing to ask of someone tho so it’s cool he trusts u enough to ask and ur cool too for taking the time to think it over.