Albee again...A Delicate Balance at the McCarter

I just don't know.

On the surface Albee seems to know nothing about mental illness. It is terrifically unlikely that someone will become schizophrenic in their late 60s. If he doesn't know that he should read up a bit.

But I suspect he does and his character is just using it as either an affectation or a coping skill as she remains married to a man who desires all around him to be dependant...on him, and at odds with each other, while looking like a long suffering and tolerant saint.

Nope it's not Agnes who controls the family dynamics, it is Tobias. He is the fulcrum about whom all action pivots. And it's not pretty.

Agnes is a dependant wife a la 1960s. We have no idea what income she may have from her late parents, but we are led to believe that she and her odious sister Claire have nothing without Tobias.
Agnes characterizes herself as the implementation phase of Tobias' wishes, the nurse to his doctor role and this appears to be true. She is not even able to relieve herself of a sister who freely states she wishes her dead...DEAD. She must tolerate this vile but cutesy-wootsey alcoholic, because Tobias says so, he allows it.

He allows, and aids and abets Claire's alcoholism. No one in the play sees the drinking as benign, even Tobias who encourages it in a classic double bind way. "Why did you quit AA, here have another," which mirrors his interaction with his best friend "I don't want you here, but stay!"

Tobias encourages people to dislike each other, but love him. And if he pays the bills and encourages dependence, you have to behave. If the man was nice you could say, people take advantage of the agreeable gentleman, but this is a guy who killed his cat because he "didn't love me." Not because it was ill, cachetic or incapacitated, but because he perceived a lack of affection.  Love me or I'll destroy you.

Sociopaths can be charming. Never forget it.