So no, of course it isn't the answer, but I think it's worth paying attention to the fact that we are, as you say, "much more attuned to nature than we are generally aware." We might try adapting to the season by either simply expecting less of ourselves and our partners in the depth of winter a winter break, as it were or bringing our opposable thumbhaving, tool-using human best to bear on the problem. Try (or rather suggest to your friend that he try) light therapy, as prescribed for seasonal affective disorder. And why do you think the midwinter tropical vacation is so popular? Surely froofy umbrella drinks are available in the frozen north; there must be another, better reason for heading to summerier climes with your sweetie as the days get short and dark. Failing that, we could do what sensible large fauna (and many types of flora too, come to think of it) do when the weather gets nasty: hibernate.
Andrea is home with the kids and going stir-crazy. Write her a letter! Ask her a question! Send her your tedious e-mail forwards! On second thought, don't do that. Just ask her a question.