Idiom 169: put up a good front

어떤 상황에서 그렇지 않은데 그런것처럼 하는 때가 있으실 것입니다. 행복하지 않은데도 행복한 것처럼 할 때 쓰는 표현입니다.

put up a good front = pretend tp be happy = fool people about one's status

Even though she is upset about the fight she had with her friend, she put up a good front and smiled the whole time they were together.