W. Somerset Maugham said this quote

“ In the first place it's not true that people improve as you know them better: they don't. That's why one should only have acquaintances and never make friends. An acquaintance shows you only the best of himself, he's considerate and polite, he conceals his defects behind a mask of social convention; but we grow so intimate with him that he throws the mask aside, get to know him so well that he doesn't trouble any longer to pretend; then you'll discover a being of such meanness, of such trivial nature, of such weakness, of such corruption, that you'd be aghast if you didn't realize that that was his nature and it was just as stupid to condemn him as to condemn the wolf because he ravens or the cobra because he strikes. ”