Final answer:
The phrase 'intrudes upon another' fills the blank, suggesting an unwanted or uninvited presence. This can cause social discomfort as seen in narrative examples where characters encounter others imposing on their space without permission.
Step-by-step explanation:
When one intrudes upon another, they are not wanted around or invited. This sentence describes a situation where someone is present in a space or situation where their presence is not desired or authorized by others. It can often lead to uncomfortable or unwelcome social dynamics, as the uninvited individual might be imposing themselves in personal or sensitive situations.
The excerpts provided from various narratives illustrate scenarios where characters are confronting social boundaries and the awareness or lack thereof in respects to being accepted or included. Whether it's an unwelcome suitor, a clash of personalities at a social event, or the breach of societal norms, these examples reflect the tension that arises when one imposes upon another without an invitation or welcome.