Complex sentence: When he was 19, Riley met 15-year-old Marlene Olive while dealing drugs at her high school, developed a crush on her and began to pursue her, giving her free drugs and gifts and doing favors for her.
Split into simpler sentences: When he was 19, Riley met 15-year-old Marlene Olive while dealing drugs at her high school. He developed a crush on her and began to pursue her, giving her free drugs and gifts and doing favors for her.