“…they stumble that run fast.”

This quote from Friar Lawrence is a warning of a sort to Romeo and Juliet about their future and their fate. When he says “…they stumble that run fast.” he is trying to portray that rushing into things does not end well usually. This is referring to the fact that Romeo and Juliet intend on marrying very early into their relationship, that they have just met and may not be as long-lasting as they think. The relationship between Romeo and Juliet  would need to be private as their families are enemies, rushing things tends to cause mistakes which would be unwise in their position. This quote is not only a short-term warning but a long-term as well. It is an early hint that bad things are bound to happen in the future of the play like their inevitable death.