I think the major factor that is causing complexity between the two star-crossed lovers is the bitterness that is contained within the two families. The bitterness in between the two families is causing both Romeo and Juliet stress in knowing that they will not be together due to strong conditions. The bitterness is briefly described in the prologue as," From ancient grudge break to new mutiny".
An example of this opinion is quoted on page 71, lines 136-137.
It quotes," His name is Romeo, and a Montague,
The only son of your great enemy."
The love that is held between Romeo and Juliet is causing the two families to escalate their hatred toward each other, and causing the restraining condition between Romeo and Juliet to be stronger. To amplify this problem even more, Romeo and Juliet discovered their profound love at the same moment when Juliet was arranged to marry Prince Escalus. Friar Laurence believed that the marriage between Romeo and Juliet would end the family bitterness, but in reality it was the opposite. An example of this opinion is described on the Scene Summary, on page 99. It reads, "Friar Laurence is willing to perform the marriage-he loves Romeo as a son, and he hopes this marriage will end the Montague-Capulet feud."