Maybe you should have a 'house meeting' each week where you can exchange points of view about how the flat-share is progressing.

I lived in a flat-share many years ago, and it was just the same then. Some girls were neat, clean and tidy and others were more laid back.

You'll have to agree to disagree on many things, but you do need to let this girl know, in a friendly and unconfrontational way, that she is being too nit-picking for the rest of you.

Call a meeting and get everyone to prepare by writing a list. Does this make sense?

FG