I always see a mix of love and sadness in his eyes

I know he’s in love with me. I honestly don’t think there’s anymore he can do to show that he is. But I always see the pain he has to live with in as well. If anything, this mix of devotion and infatuation just stuns me. How can someone who has suffered through so much for most of his life still fall so passionately in love? With me, of all people?