粋がる

プログレッシブ和英中辞典(第4版)

いきがる【^▲粋がる】

assume [put on] a brave manner

去った恋人に未練はないと彼は粋がってみせた
He put on 「a brave front [a show of bravado] by saying that he never missed the girl who had left him.

粋がるなよ
Don't put on airs!

出典　小学館「プログレッシブ和英中辞典(第4版)」