When you first start learning how to say no, you won’t know how to do it politely.
This means that you’ll offend people. Even when you have every right to say no. Even when everyone agrees that it’s ok to say no.
Asserting boundaries politely is a skill worth acquiring, if you can do it. But that takes time and practice. It’s something that’s learned alongside learning how to have boundaries; it’s not something you can learn first as a prerequisite for being allowed to have boundaries.
And when you haven’t figured out how to say no politely, the reactions you get might look to you like evidence that you really *can’t* say no. It might look to you like you have to choose between having no boundaries, or hurting people in unreasonable ways.
This is especially true if you are a disabled person who has learned to pass as nondisabled by following rules. A lot of disabled people are taught that they must pass at all costs, and taught not to asset boundaries as part of this. Starting to learn to have boundaries will probably undermine your ability to pass. That can be terrifying, and some ways people react might be triggering. But you’re ok. You’re not broken. You’re allowed to have boundaries, even if it means looking weird. Even if it breaks rules. Even if people are offended. You are a person and you have rights.
The rules for politely asserting boundaries are really complicated. It takes time and practice to learn these rules. And not everyone can master them. And even people who can have to be rude sometimes in order to have boundaries, and that’s ok too. Being able to be polite is not a prerequisite for having rights.
It’s ok to say no, and it’s ok to have a rough time learning how.