Marilyn and her husband divorced 5 years ago, when their son, Avery, was 9. Although Avery had some short-term difficulties following the divorce, he continued to do well in school, maintained positive relationships with his peers, and remained close to both of his parents. However, as a single parent, Marilyn has not been able to exercise as much oversight over Avery as she did before the divorce. Within the last 6 months, Avery has begun to engage in a number of problematic behaviors, including smoking, drinking alcohol on at least three occasions, and leaving school early without permission. Avery's behavior may be due to ______.