What are the two words “Delighted in” and “With”. I am so disappointed that I can’t express my feelings till now. Why, in the aforementioned case, I think the object of preposition has human being. At the root, not even the words: I’m disappointed as to who you are. In such cases, the object of the preposition must be “something”: I’m disappointed at/about the result of the exam, not: I’m disappointed in/with the result of the exam.