He really cares about what you think. Whenever he needs help, he knows he can come to you. He knows you won’t judge him or tell him ‘I told you so’.
He knows you’ll help him as much as you can. When he needs advice, he will seek yours because he knows that you will do your best to give him a suggestion that is in his interest.
He likes the way you think and he respects your thoughts—that’s why he wants to hear your opinion.