In romeo and juliet why doesn't juliet want to marry paris

She wants to make the decision on her own. She is also only interested in Romeo.

In "Romeo and Juliet" by William Shakespeare, Juliet never says that she dislikes Paris or finds him arrogant. (In Act 2, Scene 4, the Nurse tells Romeo that Juliet can't stand Paris. Juliet herself never says so.) But by the time her father announces that he has arranged for her to marry Paris, Juliet is already secretly married to Romeo. If she went through a wedding ceremony with Paris, the marriage would not be valid, and if she went to bed with Paris, she would be cheating on Romeo, the husband she loves.
Hope this is of great help to you, and happy studying~!
~Mistermistyeyed.