Having a third wheel on your holiday

We got a message from a man who was supposed to be going on a couples holiday with his wife and their friends. The other couple have recently separated and now the woman is still planning on coming alone. He doesn't want a tag along on their holiday but his wife feels bad for her and doesn't want to tell her not to come as she's going through a tough time. Do you think he's being unreasonable to not want a tag along on their holiday?

See omnystudio.com/listener for privacy information.