It should be socially acceptable to tell people to shut up

There's a person I used to work with. She's very kind and friendly and sweet. She's a genuinely good person, and she means well, but sometimes she just won't shut the fuck up.

I don't mind listening to someone talk, I really don't. But sometimes you have to welcome people into the opportunity to talk about things that are going on in their lives. Usually this comes in the form of a question like "What's up?" or "How are things going?" or "What are you up to?"

This person I used to work with will overhear conversations between other people, and step in to share a story that is better because it effects herself in a personal way, sometimes cutting someone else off before they are finished with a story their telling that the listeners have been engaged in. I don't think this person realizes she's doing it. I don't know if she had a lot of friends growing up to keep her in check with this kind of stuff. We can excuse it a lot of the time, but when it's literally every time she is present in the room, it's gotta be stopped.

I wouldn't want to hurt her feelings, because she hasn't done anything that she understands to be offensive. But sometimes she forgets that she has the floor in a conversation for much longer than anyone else. She needs to be told to shut the fuck up once in a while and listen for a moment so other people can speak too. But there's literally no way to do it that isn't going to sound rude to her.