Romeo and juliet

In the play Romeo and Juliet, where do u think there are gaps?
e.g. such as why did romeo and Roseline break up? or what started the Capulet and Montague's feud?
You are unable to change to change the ending and it cannot alter the relationship between characters
(Please excuse the spelling mistakes)
:)please help i need to pick a topic to do and essay on!!!!!!!!

They didn't even date. I think it's because she wanted to be a nun or remain a virgin or something like that.