〜くせに

Meaning

Expresses, with a tone of criticism or mockery, that reality contradicts what would naturally be expected from what was just stated. Close to "〜のに" but carries the speaker's dissatisfaction or contempt toward the other person; a somewhat casual expression.

Examples

知っているくせに、知らないふりをする Even though he knows, he pretends not to.
自分ではできないくせに、文句ばかり言う He cannot do it himself, yet he does nothing but complain.
本当はうれしいくせに、素直になれない He is actually happy, yet he cannot be honest about it.