I don't have a definite answer for you. It could be at any point where the story builds up enough tension or when there's a major conflict that makes him reflect and regret. Sometimes, it's a gradual realization that happens over several chapters.
Well, you could try doing things he likes together to strengthen the bond. Also, showing appreciation and support for him can go a long way. Sometimes, small gestures of love and care can make a big difference.
One way could be to have heart-to-heart conversations regularly, listen to his perspective, and work on resolving any conflicts together. Surprising him with small gestures of love and support might also make a difference.