That Romeo sure is fast because the next thing we know, Romeo tracks down Friar Laurence, who has been out foraging for medicinal plants and herbs for one of his concoctions. (Note: What we now refer to as "holistic" medicine seems to be one of Friar Laurence's favorite hobbies but, historians (like Andrew Crislip) also tell us that it wasn't uncommon for clergymen to practice or dabble in medicine – after all, a visit to the physician was an expense that many people couldn't afford and priests often needed to supplement their income.)
Friar Laurence delivers a speech about how herbs and plants have the potential to be healing and medicinal, but if they're misused, they can be deadly poison. [Get your highlighters out, because this is important. Check out "Symbols" if you want to know more.]
Friar Laurence looks at Romeo and notices that loverboy hasn't "been in bed tonight" and assumes that he must have finally hooked up with Rosaline. He also notices that Romeo is suddenly cheerful after weeks of moping around.
Romeo announces that he's over Rosaline and wants to marry Juliet. Will Friar Laurence perform the ceremony?
The Friar's response: "Holy Saint Francis!"
Friar Laurence provides a much-needed reality check. Romeo has been switching girls like highway lanes. Why, just the other day Romeo was crying over Rosaline. His tears haven't even dried yet and now he's talking about Juliet.
Finally, the Friar decides to help Romeo out but not because he's a romantic. Friar Laurence flat out tells us that he's got political motives – a marriage between Romeo and Juliet might reconcile the two warring families.
So, in the name of reducing the yearly street-brawl-murder rate in Verona, Friar Laurence skips the lecture on fidelity and commitment and goes right to agreeing with the marriage.