Original sentence: It's quickly discovered that she is married to Derek Shepherd, but because of his absence and his lack of interest about their marriage, Addison cheated on him with his best friend and Derek left her, leaving Seattle, and accepted a job proposal from Richard Webber
Edited sentence: It's quickly discovered that she is married to Derek Shepherd, but as a result of his absence and his lack of interest in their marriage; Addison cheated on him with his best friend and Derek left her, and their home in New York, and accepted a job proposal from Richard Webber in Seattle