I don't think both spouses need to be "gung-ho" on attending Retrouvaille. But on the other hand, the more willing she is to go, the better. Retrouvaille does ask if the relationship with the OP is over before you go. They have found that those with on-going affairs are less likely to benefit from the weekend.
I wish you luck with getting her there. And don't feel bad, I wouldn't go to a mid-Atlantic beach in the winter either. Unless you are a landscape painter, a windy, cold beach is not a fun place to hang out.
