Complex sentence: Miley is still mad at Jake for leaving her for six months, so when he returns, she is not pleased, becoming even more irritated when Jake sends her lavish gifts in order to try to win her back.
Split into simpler sentences: Miley is still mad at Jake for leaving her for six months, so when he returns, she is not pleased. She becomes even more annoyed when Jake sends her lavish gifts in order to try to win her back.