Amy Dickinson is a general advice columnist.
DEAR AMY: My niece lost her mother (my sister) when she was 10 years old. She is now 16 and spends time at my home with my husband and me (once or twice a month for an overnight). We do not have children of our own. This is becoming a great source of stress for me because although my husband says he is OK with her staying with us, he always ends up getting offended by something she does. To me these things are normal teenage behaviors, such as giving one-word answers or not cleaning up her dishes or making her bed. Today he was upset because she made brownies and did not offer him any. My husband and I always end up fighting once she leaves because he complains about her, and I defend her. I have spoken to her about the things that bother him, but she always seems to do something that annoys him.
-- Agitated Aunt
DEAR AUNT: The reason parents tend to be tolerant of "normal teenage behavior" is because they have learned how to pick their battles.
Your commitment to your niece is commendable. Encourage your husband to have a positive stake by taking a "team" approach, with the two of you making choices together. If he changed his perspective even a little bit, he would embrace this opportunity. As it is, his concerns seem quite petty, but I believe he is acting out because he lacks a more defined role with her and he doesn't know what else to do.
Do not offer a knee-jerk defense of her. If he has something to express, you should strategize together about how to do this -- kindly and carefully -- and then talk to your niece, together, at the kitchen table.
One night soon, take her aside and say, "Let's do something nice for Uncle Derrick and surprise him tonight with his favorite meal. I'll show you how to make the entree, and you show me how to make the brownies." I know this sounds hokey, but sometimes the way through someone's tough outer shell is to do something obvious, thoughtful and sweet.