When she saw her ex-boyfriend with someone new, the green-eyed monster reared its ugly head.

彼女が元彼を新しい人と見かけたとき、緑色の目の怪物が醜い頭をもたげた。

He tried to hide the green-eyed monster, but his anger was obvious.

彼は緑色の目の怪物を隠そうとしたが、彼の怒りは明らかだった。