What does it mean to shut someone out?
Native speaker’s answer
Rebecca
"to shut someone out" means to emotionally exclude someone/something, or to put up a barrier between something/someone. In this case, the speaker wants to know why her sister is keeping an emotional wall or barrier between her and the world, meaning that she doesn't share her personal feelings with others and keeps her distance. Ex. My sister is quiet and hard to approach, she tends to shut people out. It can also mean to exclude or put up a barrier in the physical sense. Ex. My dog accidentally locked my front door and I couldn't get in, so I was shut out of the house.