At the end of the story, Romeo decided to kill himself because he felt empty and senseless without Juliet. Taking this into account, we can say that love led Romeo to lose his mind and end up his life.
Friar Lawrence's letter fails to reach Romeo, so he assumes that his wife is dead. He rushes to Juliet's tomb and, in deep grief, drinks a vial of poison. Moments later, Juliet wakes to find Romeo dead and kills herself due to grief. Once the families discover what happened, they finally end their bitter feud.
