I think that Friar Lawerence is trying to give them a warning. He’s kind of saying that love can be a dangerous thing and that they both know the consequences that could come. They may “love” each other so much that they would die if they weren’t with each other they might die. But if they feel like it’s meant to be then they should get together. Friar Lawerence is also very wise and is also basically saying that this marriage, well, it’s not going to really work out no matter what. The families are going to hate it so much. It’s like Hans and Ana.