My ESTJ step-mother isn’t shy in the sense of being tongue-tied in company. But she worries about what kind of impression she makes on people. She knows that she can be harsh in her judgements, competitive, argumentative, “unfeminine,” etc. So she doesn’t really have any friends or a social life. As far as I know, she doesn’t try to reach out and socialize outside the house.
That suits my father. My father’s an ISTP, so he prefers not to have much of a social life anyway. So the two of them pretty much stay home and don’t interact with people outside the family. Luckily for her, it’s a big family.