What is the difference between diversity jurisdiction and "subjectmatter
jurisdiction?

In the law of the United States, diversity jurisdiction is a form of subject-matter jurisdiction in civil procedure in which a United States district court in the federal judiciary has the power to hear a civil case

Subject matter jurisdiction refers to whether a court can hear a case on a particular subject and is usually pretty clear. Personal jurisdiction, on the other hand, refers to whether a court has power over the person being sued and can be difficult to determine.

The answer would be: unhappiness