I'm betting this is likely not the first time he has been told he is "too big". Honestly talk to them as a couple meaning both of you with both of them and see what you come up with. It is highly likely he mistook your wife's discomfort for pleasure in the moment as I gather nothing was said then nor has it until now. In fact I bet he thinks your wife had an awesome time and given the chance he would likely go at it in the same manner again. Now this does not mean he would intentionally hurt someone but unless he knows he cannot tone it down and go both slower and not so deep. Of course it is up to your wife if she would like to try again with everything said and known or if she would prefer to skip intercourse with him. That being said he is part of a couple and it may also mean his wife is not going to be willing to do things with you if your wife is not willing to do things with her husband. A lot of what happens next depends on how they feel about what you tell them and none of us have a crystal ball to see the future. You mentioned they are cool and a part of a group you play with while on a cruise so it is both likely they will take things well and with a number of partners to choose from there is likely not going to be a problem with your wife protecting herself from harm while everyone still has fun. BTW I would have this conversation before the cruise so nothing is sprung on anyone at the last moment.
