Well, I hope I wouldn't have died for Rosaline. Romeo was rash and impulsive about love. He was one of those love at first sight guys. Unrequited love (she didn't feel the same way) just made Romeo want her even more. Romeo's pining away for Rosaline is a little bit of foreshadowing for his future attraction to Juliet. We get the sense that given the right attractive girl, Romeo will be obsessed with somebody else. As for the Prince, his decree is death for any who break the peace of the streets. Romeo juxtaposes the violence of the fray with his pre-occupation with peace and love.