Question

what would be three reasons that friar lawrence is to blame for the deaths of romeo and juliet

Answer 1

Ah, first, he was the one who married them to each other instead of lecturing them on how stupid it was to get married after two days of knowing each other and at the age of around fourteen or so.
He also gave Juliet the the potion that let her fake her death.
He was also a coward for fleeing when he heard noises outside when meeting Juliet as she woke up, leading to her suicide; he could have convinced her otherwise.

Answer 2

thanks!