To save appearances

to preserve a fair outward show.
to preserve a decent outside; to avoid exposure of a discreditable state of things.

See also: Appearance, Save

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
We might live together, so as to save appearances. But to forget what had happened, or to feel satisfied with my position, was beyond the power of my will.
Wait here an hour after I have gone to save appearances; and then follow me."
But I was, what is called, putting it on, to save appearances, though the attack was a genuine one.
“ The sight is worth some little apprehension; for of real danger there is none, I will go with you and Miss Grand, however, to save appearances.”
"To see something that was Henrietta, and that is a thing we must cast out and hide, with a little superstitious mumming to save appearances. Why did you remind me of it?"
I could not tell the others of the day's discovery till we were alone, so after dinner, followed by a little music to save appearances even amongst ourselves, I took Mina to her room and left her to go to bed.