Loyalty is questionable as really the story does not show loyalty as a major theme, except in certain situations such as Romeo's avenging Mercutio's death. Romeo and Juliet, however, are not at all showing loyalty to their families as their families would see it. Friendship and love are definitely the strongest values presented in the play. The two coming together show love for each other, and Friar Laurence hopes that their love will be enough to bring an end to the feud the families have been fighting for so long.
I believe that all of that is very accurate and that the most used themes used in Romeo and Juliet is love and hatred . I say that because through out the whole story they always show one of the two themes.