Medication and Therapy - are both required?

The man I am involved with has ADHD. He is currently on Adderall and thinks that's all he needs to do. He decides what he has to do during the day and then decides when he should take his medication. Everything I have read indicates that the medication should be taken at the same time everyday to help with ADHD symptoms (distraction, hyperfocusing, lethargy, etc). Any time I ask him about that he gets very defensive and shuts down. Sometimes the things he says makes me think he may also have some depression as well and it worries me that he isn't addressing it. He has never sought any therapy either and I don't know how I should broach this subject. Any suggestions?