The Title: Love's Labour's Lost

The lover knows the one they love by the look in their eyes,

As a fan of wordplay, Shakespeare values wordplay and puns in his works so much and makes them central elements of his plays. His play Love's Labour's Lost is rich in wordplay in terms of its context and its title. 

As a literal meaning, the title suggests that the effort that's been shown to find love is wasted. In the play, four noblemen are invited by the king for a test in which they cannot fall in love with someone, but once they hear that a princess and her friends have arrived at the castle, they directly wonder about them and meet them privately. However, during one of their meetings, women show up with masks and one of the men, who is in love with the princess, sees one of her servants with a mask and thinks of her as the princess and confesses his love for her. He couldn't understand that she was a servant and not the princess, but still, he confessed his love without hesitation. The lover knows the one they love by the look in their eyes, but these men cannot find the ones they are in love with and all get mistaken by their appearances which proves the fact that courtly love has left its place to material love. People cannot recognize the ones they are in love with, but they do not hesitate to reveal their love to strangers. 

However, unlike Shakespeare's other comedy plays which end up with marriage, in this one we don't have a scene of marriage, but it ends with people's separation.