It is interesting that there is a prologue in the form of a sonnet which gives the plot away and that the Chorus delivers another sonnet prologue to Act Two but then the prologue's cease. This is a bit like the 'play within a play' idea in The Taming of the Shrew which Shakespeare also seems to have forgotten half way through.
There is also a lot of word play and other stuff going on. The Nurse is a very garrulous figure of fun. Romeo's mates, Mercutio and Benvolio, do a lot of stag-talk (eg “Draw thy tool ... My naked weapon is out”). And the servants regularly come in with some comedy. Either Shakespeare needed fillers to pad out his rather simple story or he realised that the audience would want some gagging going on before the denouement.
Romeo Montague, pining with unrequited love for Rosalind, intercepts an invitation to a feast she will be present at ... but it is hosted by his family's sworn enemies, the Capulets. Going hidden to the feast he sees and falls in love with thirteen year old Juliet Capulet and she with him. Later that night, in the famous balcony scene, they pledge their love to one another and arrange a meeting at the holy cell of Friar Lawrence to get married.
But after they are married Romeo gets involved in a street brawl and kills Juliet's cousin Tybalt. This gets him banished from the city. Meanwhile, Juliet;s parents have made plans for her to marry Paris.
Romeo steals into Juliet's bedroom to consummate his marriage before fleeing to Mantua.
Friar Lawrence now gives Juliet a potion so she can feign death rather than marry Paris. The Friar's plan is for Romeo to come to the vault, disinter Juliet, and take her to Mantua. But the Friar's letter is dismayed and Romeo only hears that Juliet has died.
Romeo returns to Verona. Entering the vault he drinks poison to be with his wife. She then awakens, sees him dead, and stabs herself with his dagger.