In Act 1 Scene 1, Romeo thinks himself "in love" with Rosaline, but he hasn't had enough experience to understand the true depth of feeling meant by the phrase. He moves effortlessly from being hearbroken over his unrequited love to being hungry to realizing that something has been going on in the area.
Romeo understands the concept of love between two individuals, but doesn't know what that can entail.
Love as loyalty to family is also demonstrated in this scene. Sampson and Gregory, backed by Tybalt and the others, pick a fight with the Montagues to demonstrate their family pride and power, the love of their position and the superiority they feel it gives the Capulets.
What, drawn, and talk of peace? I hate the word
As I hate hell, all Montagues, and thee.
Have at thee, coward!