Complex sentence: However Davina disapproves of Tia's positive influence on Tyson and is jealous of their blossoming romance, and begins to plan a terrible revenge designed to also win him back from her.
Split into simpler sentences: However Davina disapproves of Tia's positive influence on Tyson and is jealous of their blossoming romance. She begins to plan a terrible revenge designed to also win him back from her.