Once you make a decision, stick to it. He may be afraid of repeating old patterns or mistakes.
Ask yourself if you are well and truly ready to play second fiddle to his problems, and if the entire exercise is worth it. Say something like, "If you feel comfortable, I'd like to know a little about your divorce. Your boyfriend may simply want to keep things between the two of you uncomplicated for now. Include your email address to get a message when this question is answered.