(Douglas Booth; Photography by Bruce Weber)
I have to say, while respecting everyone's opinions and readings of the characters, I don't understand why Romeo gets such a bad reputation and comes off so badly in many people's analysis. (And I've heard many people express this view) The discussion of his age would certainly affect your impression of him...I know it would mine. So if there doesn't seem to be the same clear textual indication of Romeo's age as there is with Juliet's (and I certainly can't think of any), then depending upon if you think the two are roughly the same age or if Romeo is a few significant years older (or, if you're seeing the play, how the director has chosen to cast the two roles) would definitely affect how you feel about Romeo...and about Juliet, too.
I always thought of them as roughly the same age, myself. I didn't have any good reason to think that; it just seemed to be the popular idea about them that I inherited. Reading it more closely now, again, I don't see any concrete sign about Romeo's age. (All of the young men, it seems, are variously called "youth," "gentleman," "boy," etc., depending upon the circumstance and the attitude of the speaker, so I don't know how absolute those are in terms of age-markers.) I do note that in Shakespeare's source material "The Tragicall Historye of Romeus and Juliet," of Romeo the author writes that "Upon whose tender chyn, as yet, no manlyke beard there grewe." So if that was in Shakespeare's mind, perhaps that's how also thought of Romeo, but that we can never know.
Nonetheless, I still think Romeo is unfairly thought of as particularly impulsive or immature. I wonder if it isn't our desire to recognize Juliet's remarkable character that causes us unnecessarily to impugn Romeo's. Yes, Juliet shows remarkable courage and maturity in the play, and it's amazing to think of such thoughts and beautiful poetry coming from the incredible mind of a thirteen year old girl. But she also shows evidence of rashness and immaturity. She, after all, basically is the one to propose marriage to Romeo after one dances, two kisses, and some moonlit garden conversation! And this, after she'd just said in an earlier scene to her mother and the Nurse that she didn't want to get married, and wasn't even thinking about it. But we don't blame Juliet for being impulsive, and accuse her of jumping into marriage with the first good-looking boy who pays attention to her...and yet we accuse Romeo of fickleness and suppose he would've fallen in love with someone else the next week, just because he starts the play in love with Rosaline. Maybe that's true about him...but if it's true about him, it could just as well be true of her.
I wonder if a lot of our perception about Romeo doesn't come from the scene in Friar Lawrence's cell after the duel, where the Friar and the Nurse have to have some harsh words with Romeo to get him to stop crying and deal with the situation. I feel like a lot of people inevitably grow to share the adults' view of Romeo as being spineless and overly emotional. But, my word! The boy (or young man?) just watched a dear friend get murdered in front of his eyes and for which he was indirectly responsible, and then he himself in a rage murdered one of his new wife's dearest family members. The fact that Romeo is an emotional puddle just shows me that he's not a psychopath, thank goodness. He's actually really emotionally torn up by having just killed someone.
In fact, in my opinion, it's Romeo's concern with being a "man" in the way that Veronese society defines the term that precipitates the tragedy. The first couple of acts show us a Romeo who is willing to fall in love with the person of his choice, and willing to defy his family and their senseless feud to do so. After secretly marrying Juliet when Romeo meets the enraged Tybalt in the streets, he bravely and nobly tries to defuse the tension, enduring insults and the public risk to his reputation by refusing to fight, and then physically trying to stop the duel between Tybalt and Mercutio by putting own body between them. Only after his friend Mercutio is killed and he realizes that his physical intercession actually enabled the fatal blow to be struck does Romeo start to embrace all of those social views of what it means to be a "man" (“O sweet Juliet, / Thy beauty hath made me effeminate”) which, tragically here, means worrying more about his reputation than the feelings of his wife, and fighting back with a sword against the person who'd done him an injustice. As soon as he kills Tybalt, he realizes the folly of this thinking (“O, I am fortune's fool”). In other words, in my opinion, Romeo is more of a man when he's acting like an immature boy or coward, then when he acts in the way that Veronese (and our?) society expects "men" to act.
But more importantly, I wonder if it's just too a modern discomfort with large displays of emotion. And I think young men are unfairly penalized for that. Few people think King Lear is "whining" when he's on the heath and raging against the storm. And people may think Othello is stupid for being so "easily" duped by Iago, but few people think he's "whining" when he rages about his wife's supposed infidelities. And when it comes to Juliet, few people think she's "whining" when she quite often goes on about how impatient she is that things don't happen faster ("My nurse has been gone three hours, even though she said it'd be half an hour! Adults are so slow!" "Why is this day so long, when if it could just be night I'd be having sex with my new husband! Come on and get here, night!"); they often find her impatience charming. But a young man who expresses, with beautiful poetry, how much he loves this girl, how devastated he is to be separated from her, how he can't live without her...he's "whining."