Although often attributed to Romeo and Juliet, Shakespeare aficionados the world over can assure you that neither this line nor anything like it, appears in that play. It doesn’t even sound like Shakespeare. It is by Arrigo Boito, who does at least have a Shakespeare connection in that he’s written a number of operas based on Shakespeare’s work including Othello and Falstaff.
In fact, it’s precisely Falstaff where we can find the original quote (although it’s in Italian):
Come ti vidi
E tu sorridi
Perchè lo sai.
which Google Translate tells me is, “How I saw you I fell in love, And you smile Because you know it.” Close enough, Google!
Hat tip to https://falsescribes.wordpress.com/2013/07/12/when-i-saw-you-boito/ pointing out that the text is from Falstaff, which at least gives us an excuse to make the Shakespearean connection? I wonder if there are folks out there who know that’s the source and are just working backward, figuring that Shakespeare must have written it originally.
Nah. All these quotes fall victim to that same “It sounds sappy and romantic, assume Shakespeare wrote it, it will get more likes on Instagram” logic.