be no skin off someone's nose idiom (US also be no skin off someone's back)
与（某人）毫不相干；（某人）毫不在乎
used when you want to say that it makes no difference to you what someone else does or thinks
It's no skin off my nose if you don't take my advice. 你就是不听我的建议，我也一点儿不在乎。