In Romeo and Juliet, Juliet agreed to marry Paris after she spoke with the Friar. Is this an example of verbal irony?
In verbal irony, the character says something that is the opposite of what the character means. Juliet says she wants to marry him, but doesn't really mean this.
It is Act IV scene 1 where the Friar gives Juliet this advice. The thing to remember with verbal irony is that it focuses on the gap between appearances and reality. What Juliet does in saying that she is going to marry Paris isn't really an example of verbal irony because it is simply a lie. Every lie we tell isn't verbal irony. An example of verbal irony would be a student who says ironically to his friends: "I can't wait to study Shakespeare" when actually the opposite is true. Juliet agrees to marry Paris but without any irony. It is something she does very clearly to buy herself time before she can take the potion that she is given and avoid marriage.
The rule is for something to be verbal irony, there has to be irony there in the first place. It depends very much on context and the kind of situation. If there is no overtones of humor or comic intent, then it would be wrong to state that it is verbal irony.