I'm going to break the kitchen glass door
Why do you want to break a glass door?
My girlfriend forbade me to break another one so I'm doing it quietly in secret.
I see what you mean, but you shouldn't just break the door because your girlfriend forbade you. If your girlfriend finds out that you broke another door, she will likely break up with you.
So I shouldn't tell her
You should just not do it at all and leave the glass door alone. That would create a huge mess and seems pointless to do.