Bobert, you're looking for answers that don't exist. The apparent air of discontent displayed by your friends' partner has nothing to do with how wet or dry their vegetables are. In all likelyhood she has no idea what she wants or why she's so irritable but feels the need to demonstrate her discomfort by taking it out of the man in her life.
It has taken me three marriages to arrive at one certainty with regard to the female species;

SHOES!


That's it!


SHOES!


A woman has many wants and needs but none as great as her need for SHOES.
Armed with this vital piece of information you can safely navigate through the perils of a relationship in the sure and certain knowledge that however tough things get you can always take her shopping for SHOES and that everything will be made alright.

If I had my time over I would have bought a shoe shop.

C-flat.