"Kidneys are supposed to remove wastes and extra fluid in the body"
Not really; kidneys are balance organs, thats why it is two of them. Emotional problems, relationship problems etc, all related according to TMC; think fear/ adrenals as well.
Physically kidneys dont remove "waste", but they regulate whatever is to much at the moment. Like fluids,(physical variety of EMOTIONS!),water, electrolytes, Ph, chemicals.
All are relationships.