Romeo considers love cruel and fleeting in Act 1, Scene 1-3 of Romeo and Juliet.
When the play begins, Romeo is moping. His parents and friends are worried about him, because he does not seem to leave the house. Romeo says that “sad hours seem long.” Benvolio asks him what makes them long.
Not having that, which, having, makes them short. (Act 1, Scene 1, p. 5)
Romeo’s problem is that his girlfriend has dumped him. He thinks there are too many hours in a day when he does not have love. He suggests that love is madness, and fleeting.
Love is a smoke rais'd with the fume of sighs;(190)
Being purg'd, a fire sparkling in lovers’ eyes;
Being vex'd, a sea nourish'd with lovers’ tears. (Act 1, Scene 1, p. 6)
Poor Romeo suffers because he thought he was in love, but his girl decided she wanted to be chaste. To him, love is fickle and changeable.
In a way, Romeo's complaints foreshadow what is about to happen. He is about to change his mind, and fall instantly in love with Juliet. Once he lays eyes on her, he seems to not care about Rosaline any more. So love is quickly changing, but this time it works in Romeo’s favor.