Quote 1
BENVOLIO
[…] What sadness lengthens Romeo's hours?ROMEO
Not having that, which, having, makes them short.BENVOLIO
In love?ROMEO
Out—BENVOLIO
Of love?ROMEO
Out of her favor, where I am in love.
(1.1.168-173)
Way to be totally emo and enigmatic, Romeo. Here's he's completely infatuated with Rosaline. When he's not daydreaming about Rosaline in his room, He's moping around in a grove of "sycamore" trees, where those who are sick amour (sick with love) tend to hang out (1.1). The thing is, Rosaline has absolutely no interest in Romeo, but he pursues her anyway. Maybe he's not in love with Rosaline as he is obsessed with the idea of being in love—
Quote 2
BENVOLIO
I pray thee, good Mercutio, let's retire.
The day is hot, the Capels abroad,
And if we meet we shall not 'scape a brawl,
For now, these hot days, is the mad blood stirring.
(3.1.1-4)
Benvolio, who always seems to play the role of peacekeeper in the play, wisely notes that a "brawl" will be inevitable if they meet up with the Capulets. According to Benvolio, violence is always inflamed by the summer's heat.
We interrupt this program for a brain snack: rates of violence increase during periods of hot weather source (source). Thank goodness for air-conditioning.
Quote 3
BENVOLIO
Blind is his love and best befits the dark.
MERCUTIO
If love be blind, love cannot hit the mark.
Now will he sit under a medlar tree
And wish his mistress were that kind of fruit
As maids call medlars when they laugh alone.—
Romeo, that she were, O, that she were
An open-arse, thou a pop'rin pear.
(2.1.36-41)
Mercutio reduces love to sex, using a crude fruit metaphor to show that sex itself is ridiculous.