I was exactly the same as your wife when we lived in the UK - almost went into hibernation mode in the winter, and got ulcers on my fingers from the cold! Yes, it does feel relatively cold here in the winter, especially when you have been here a few years and acclimatized, but bear in mind that we have had one of the coolest winters here this year, and I have only worn a coat about twice. We keep a few rugs in the lounge for the evenings, and I frequently sit under one of them in the evenings when it feels really cold, but we very very rarely get those dark and dreary days where it feels like it hasn't got properly light all day, which you may find makes all the difference to your wife! I often rug up to take the dog out on winter mornings, in hat, scarf, gloves, fleece.......and sunglasses!
The snow mentioned above was an exception rather than an example of how cold it gets on a regular basis! It was so unusual it made the news! Even then, we didn't get any in suburban Adelaide.