Romeo didn't really love Rosaline. He as just playing at being in love, being what he thought guys in love were like. When the real thing came along the Rosaline fantasy vanished into thin air.
They fall in love at first sight
Early in the play, Romeo and Juliet meet at the Capulet's party and they both fall in love at first sight.
she overheard him
Juliet
Romeo and Juliet meet, fall in love, and get married.
Romeo. Hence the name "Romeo and Juliet"
It was love at first sight :]
Juliet quickly admits her love for Romeo on the balcony because she is overwhelmed by her feelings and cannot contain them any longer. Their forbidden love adds to the intensity of their emotions and compels Juliet to confess her love despite the risks involved.
They fall in love at first sight
Early in the play, Romeo and Juliet meet at the Capulet's party and they both fall in love at first sight.
she overheard him
The Capulets throw a big feast in Romeo and Juliet where Romeo and Juliet first meet and fall in love.
Juliet
She agrees with him so quickly because she's obsessivly in love with him so she ignores all his flaws.
They died.
He imagined himself to be in love with Rosaline, but Juliet was the real thing.
Romeo and Juliet meet, fall in love, and get married.