Complex sentence: The next day she talks to her boyfriend over the phone and relates on how she came to acquire the dog, he becomes angry since they initially met when she ran over his dog accidentally some years before, he wants her to take the dog back.
Split into simpler sentences: The next day she talks to her boyfriend over the phone and relates how she came to acquire the dog. He becomes angry since they initially met when she ran over his dog accidentally some years before, and wants her to take the dog back.