Shakespeare presents several different understandings of romantic love in Act 1. We see a couple of notions presented through his characters Benvolio and Mercutio.
Benvolio is the only practical character in the play. The only one with a head on his shoulders, who is not driven purely by his emotions. Hence, Benvolio's notion of love is much more practical than either Romeo's or Mercutio's. On the one hand, Benvolio empathizes with Romeo's pain due to being rejected by Rosaline, declaring how sad it is that love should prove to be "so tyrannous and rough in proof!," meaning that love should prove to be so oppressive and harsh when it should be such a gentle emotion (I.i.168). However, beyond empathizing with Romeo in his pain, Benvolio believes that one does not have to allow oneself to be overcome by love. We can still be rational, thinking human beings. We see Benvolio's view when we observe him telling Romeo, "Be rul'd by me: forget to think of [Rosaline]" (227). In other words, if Benvolio believes that Romeo can put his heartache behind him and forget about Rosaline, then Benvolio believes that one does not have to be controlled by love or any other emotion. Benvolio's view on love is that we can be just as rational concerning love as we can with anything else.
Mercutio's take on love is a bit different. Out of the three young men, he is one who actually doesn't believe in romantic love. He treats romantic love as a joke, as we see in his mocking response to Romeo for saying that he cannot dance because his heavy heart is making his feet like lead. Mercutio mocks Romeo by comparing him to Cupid, saying, "You are a lover. Borrow Cupid's wings / And soar with them above a common bound" (I.iv.18-19). Not only does Mercutio view love as a joke, he views it merely as an avenue for sexual pleasure, as we see from his many sexual innuendos. We see one sexual innuendo in his line, "Prick love for pricking, and you beat love down" (29). While on the one hand, Mercutio is telling Romeo to cease allowing love to break his heart, the word "prick" and gesture of "pricking" can be interpreted sexually. Hence, Mercutio's notion of love is that it is a sexual joke.