Why do I get jealous over a girl even though I don't want to be with her at all?

 The clause in the sentence "I am afraid that" is a noun clause. A noun clause is a type of dependent clause that can function as a noun in a sentence. It can be the subject, object, or complement of a sentence.

In the sentence "I am afraid that," the noun clause is "that." It is the object of the verb "am afraid."

Here are some other examples of noun clauses:

I believe that she is telling the truth. (noun clause is "that she is telling the truth")

I want to know what you are thinking. (noun clause is "what you are thinking")

He is surprised that you didn't come. (noun clause is "that you didn't come")

Noun clauses can also be introduced by other subordinating conjunctions, such as "because," "whether," and "although."

I hope this helps!