The strong emotions that Romeo and Juliet feel for each other is more of an infatuation than real love. Infatuation is characterized as a rash, sudden, intense passion. It tends to end just as suddenly as it begins. Real love, in contrast, is more of a choice than just a feeling. It's an active choice to continue to love and value a person despite his/her faults. Friar Laurence is especially used by Shakespeare to help classify Romeo and Juliet's love as infatuation.
Friar Laurence especially characterizes Romeo's love as being mere infatuation by pointing out that he is far too young to truly know what real love is. Friar Laurence especially thinks Romeo is too young due to his fickle nature. He has very suddenly switched from loving Rosaline to loving Juliet simply because he associates love with physical attraction, which Friar Laurence points out in his lines, "Young men's love then lies / Not truly in their hearts, but in their eyes" (II.iii.68-69). Since Romeo is loving with his eyes, he is not feeling real love, but rather infatuation. Friar Laurence further asserts that Romeo is far too young to understand real love when Friar Laurence states that Rosaline was right to reject Romeo, seeing herself that he was too young. Friar Laurence uses a metaphor to compare Romeo to a toddler that reads from memory rather than actually being able to read in order to make his point that Romeo is far too young to know what real love is, as we see in Friar Laurence's line, "Thy love did read by rote[memory], and could not spell" (91).
Not only does Friar Laurence express his view that Romeo and Juliet's love is more of an infatuation by pointing out that Romeo is too young to know real love, he also warns the couple just before he marries them that the type of intense passion they feel for each other is likely to die just as suddenly as it begins, as we see in his lines, "These violent delights have violent ends / And in their triumph die, like fire and powder" (II.vi.9-10). Since the feeling of intense passion that begins suddenly and ends just as suddenly is a symptom of infatuation, we know Friar Laurence is warning the couple that what they feel for each other is merely infatuation.