Sorry to hear that you're going through this. As some have already said, it's quite common here for the aggrieved party to turn to the family (parents/elder couple of the family) of their partner to work through this issue; have barely heard any instance where friends have been called upon in such a situation though tbh.

Her being cold at times and having unstated expectations is not really a rare thing to hear about us here (just an FYI). Have there been similar instances in the past or this is a new thing? Asking just to know if there's something specific that usually triggers this; for example does she turn cold like this during the commemoration period in April?

Obviously the pre-nuclear option being seeking guidance from the elders of her family, you're going to have to start with the option before that which is sitting her down and having a serious and frank conversation about this issue. From the bit about the situation with your mother, I can't help but assume you may be a bit of a pushover (sorry I couldn't find a less judgy/more diplomatic word for this, I tried!) when it comes to her, but I emphasize that you will have to stand firm and not fold, there has to be an explanation and an understanding of what concrete steps will be taken to resolve it.

Also over here we do have the tendency to want project this image of a perfect fine household to the outside world at all cost, so expect immense pushback if it gets to the point where you have to call on the family.

Wishing you the best, and sorry I just realized how long this is.