I think that a clear case can be made to reflect that Romeo is depicted as a character of pure emotion. There is an affectual side to Romeo that is quite evident even in the earliest phases of the play. When Lord Montague describes him as "his own affections' counselor," it highlights the strong sense of emotional affect that is within him. We see this throughout the play. At the outset of the play, there is a melancholy that impacts Romeo. There is not a clear reason as to why he feels what he feels, but it is evident that he "feels" and this helps to establish a baseline for the character that is fairly constant throughout the drama. His infatuation for Rosaline, the immediacy in which he is enamored with Juliet, his intensity regarding the killing of Tybalt, and the strict desire to escape with Juliet, all reflect an emotional intensity that is inherent in his character. In the couple, it seems as if Romeo is the heart while Juliet is the "brains" of the operation. Romeo is shown to be extremely emotional and lacking moderation in feeling and displaying these emotions.
Thorough out the play, he is presented as immature and of impulsive nature. Even Friar Lawrence claims his love as doting not loving.