turn one's back on [看美剧学俚语loki s02e01]

Ma'am, I know how hard it is to turn your back on everything you've believed in.

turn one's back on,表面意思是 背对,背朝 ，这也是引申意义的来源。

1 turn one's back on sb 对人

拒绝帮助某人,对某人撒手不管,不理会
Don't turn your back on me, I need your help.
别拒绝我，我需要你的帮助。
I don't think he would turn his back onhis brother, whatever he was accused of.
不管人们怎么说他，我觉得他不可能不管自己的兄弟。

2 turn one's back on sth 对事

背叛，背弃，抛弃，远离
He turned his back on his family.
他抛弃了自己的家庭。

In his twenties he turned his back on his Catholic faith.
20多岁时，他背弃了自己的天主教信仰。