Answer:
Friar Laurence is at first confused by Romeo's request to marry Juliet, since, the day before, Romeo had been complaining to him about the fact that Rosaline would not reciprocate his undying love. However, Friar Laurence agrees to marry the two young lovers, mostly in the hopes that this secret marriage will end the lengthy Capulet-Montague feud. (His plan does ultimately end the feud, but certainly not in the peaceful, painless way he was expecting.)