Why did Juliet forgive romeo for killing Tybalt?

Juliet never forgives Romeo for killing Tybalt. In fact, she is initially filled with rage and grief when she learns of her cousin's death. She calls Romeo a "villain" and "murderer," and she even wishes that she could kill him herself. However, as the play progresses, Juliet's feelings for Romeo begin to change. She comes to understand that he killed Tybalt in a fit of passion, and she eventually forgives him. This is evident in the scene where Juliet and Romeo are reunited in Mantua. Juliet says, "I forgive thee willingly," and she embraces him.