"So smile the heavens upon this holy act That after-hours with sorrow chide us not"(2.6.1-2)
Romeo and Friar lawrence discussing the wedding
"Amen, Amen but come what sorrow can, it cannot countervail the exchange of joy that one short minute gives me in her sight." (2.6.3-5)
Friar lawrence and Romeo are discussing the union and he advises them
"Do thou but close our hands with holy words, Then love devouring death do what he dare, It is enough I may but call her mine." (2.6.5-8)
Friar Lawrence does not belong to a family, however he is very close with Romeo, Romeo trusts Friar Lawrence. When Friar lawrence agrees to joining the two he is rebelling against Romeo.
Although Romeo wants to be married Friar Lawrence does it out of pure self interest and greed in an attempt to stop the feuding families even though he knows that their union will cause great unrest and devastation to the families.
By not advising Romeo how much pain this decision will cause he is defying Romeo.