One time I was travelling SYD-SIN on SQ. I went to take my seat and a guy was there (economy) who said he would like to sit next to his wife.
The seat he offered me was in Business. We both cleared it with the Purser and I had a very comfortable flight. The crew were amazed he was happy to sit in economy and give up a good seat. I expect it was company travel and had to pay for his wife.