Ugh, we're going through a similar thing... we moved from a super concrete apartment downtown to a house on a 5 acre block... and our electricity bill went from like $30 a month to $300... and while I don't know for certain, I'm sure it's the central heating.
I work from home, and have a tiny little heater in my study, and like you I've got jackets and gloves on... but when my partner comes home she blasts the central heating for hours until she goes to bed. I'm trying to work out ways to curb that, but haven't found a solution yet. $600 in 2 months is pretty much where we're at too... and yeah, winter hasn't truly hit yet. We're in OR.
Wow. Having lived in CA so long, and Hawaii before that, I hadn't realized that heating prices were so high in parts of the country that get real Winter. That these are normal prices is just incredible.
Well, hope you figure something out. Maybe convince your partner to start wearing long johns under her clothes in the evening? They make silk ones. Or a hot water bottle. They make some pretty jewel toned ones and if you keep one on your lap in the evenings it really makes a difference. I have all that from many years ago when I lived in a place in CA with no heat (while I was saving up to buy my first house). Thankfully I held onto it all and have been using it the last day.
Thanks! I've just gotten her some electronically heated socks and a top that she can bluetooth from her phone. No idea if it's terrible or useful, but if it doesn't work then yes, long johns it is! She will be spending 3 weeks over Christmas and New Years in Australia, so she'll have a chance to thaw out.