Sounds like she is just trying to twist the knife, attacking any possible crumb of sanity you have to hold on too. So it isn't about the coffee maker. It could have been about anything like bringing home the wrong brand of carrots for stew or leaving your dirty socks out.
Lord knows what triggers them. My exBPDgf was more the quiet type. I only saw silent treatment in the end and she left. I didn't have a chance to practice the tools in the workshop here. I wish you better luck. You being out of town could be fortuitous. Let her self soothe, read up here and enjoy your freedom abroad.
