The Friar has an idea that marrying them will end the feud. He doesn't really think this through, since the marriage cannot affect the feuding families unless they know about it, and the Friar does not have the courage to tell them.As for the nurse, she is Juliet's servant and has been since Juliet was a baby, and Juliet asked for her help. Of course, she was happy to do it, since she delights in the possibility of Juliet with a man--any man--Romeo or Paris, who cares?