I've continued to think about this and would like to add that I do not mind my husband being friendly with women, or being out in a group with women, but I would not be at all happy if he went for long country walks alone with another woman, or paddling on the beach with her. These ventures seem to be the stuff of romance and I would, actually, be very upset.
If hiking and paddling are to remain on the menu, then I think that others will have to be involved ~ preferably his wife and your hudband ~ and a few other couples, perhaps.