I think you should definitely break the cycle of going on holiday together with this couple. I wonder why you have invited them to stay with you for a week? That is a long time to have someone miserable in your house, where there is no escape. At least when you are away you could opt to spend days separately, or have a meal out without them.
If the two ladies are good friends, then why not stick to ladies only get togethers. Ask his wife whether there is a problem. She may be relieved to be able to offload.
I have just come back from the hairdresser feeling fairly upbeat, to find that DH is miserable because he had to see a student before he saw his GP. Also he has managed to agree a date with a tradesman forgetting that we are going to be away just then. Nothing is right, he is a grumpy old man. Often he is in pain and it is hard to be upbeat when you are in pain, but often being grumpy is just the way he is.
When we are with other people for a short time he is lovely, polite, friendly, but if he had to keep it up for very long he would revert to type. Maybe your friend’s husband is like this, and she needs your sympathy.