Brother-in-law sent me message

My brother in law sent me message last night. He asked me some questiones.the first is: what kinds of character I think my sister is, the second is: who is the accommodating one I think in their marriage life, the last questiones is: if I exchange the position with my sister, will I choose him. I told him, my sister is mainly an outgoing woman, and sometimes she behave as conservative. I think every one has two sides of character. Because my sister is seven years elder than her husband, so I think my sister is the accomodating one. I don't know how to answer the last question, I didn't answer him. but I won't choose a man who is younger than me as my husband. because I am afraid the younger husband will abandon me when I look old. the other reason is the generation gap between two people who born in the different era.
 
I guess something must be wrong between my sister and her husband. But my brother in law just told me they were fine. but I don't trust what he said. Hope they can solve the problems by comunicating to each other.
.