Explain the dramatic irony in Friar Lawrence's speech at Act 2, Scene 3, lines 65-83 of Romeo and Juliet.

Dramatic irony is a literary feature that is very
prevalent in Shakespeare's play Romeo and Juliet. It's also a
literary technique that drives the plot makes the audience or reader feel as if they are
part of the action and are privy to information other characters do not yet know.
However, there is no dramatic irony in the lines you are asking about. By the time the
Friar speaks the lines you are referring to, he already knows that Romeo is no longer in
love with Rosaline and is now in love with Juliet. However, there is dramatic irony in
this scene, but it occurs at the beginning of Act II, Scene
3.

In the beginning of Act II, Scene 3, Romeo finds Friar
Laurence tending to his herb garden, a hobby and passion the Friar takes seriously and
is very knowledgable in. In fact, these herbs he knows so much about come into play in a
major way later in the plot. Romeo has just come from Juliet's home. This is the morning
after they have professed their love for each other after the Capulet ball and have
decided to marry. Romeo can't wait to tell the Friar about the change of events, being
that the Friar is Romeo's father-figure in the play. The Friar thinks Romeo is still in
love with Rosaline. What the Friar doesn't know that we, the audience/reader already
know, is that no longer covets Rosaline. He is now in love with
Juliet.