On the bus

There was an interesting thing happened on the bus which I usually take every morning. After a man got on the bus, he asked an old woman who sat next to him," Where is your husband?" "No. He is my brother, not my husband." That old woman answered very angrily. I did not know if somebody else heard that conversation, but I overheard. Before this morning, I also thought the old man who usually goes with the old lady was her husband. I was very surprised, and then decided not to guess the relationships of some people who I usually meet.