脸上下不来to offend somebody

• 本想当面说他两句，又怕他脸上磨不开。

  I originally wanted to have a go at him face to face, but I was afraid it would offend him.

不好意思to feel embarrassed

• 觉得磨不开

  be embarrassed

• 这么办我觉得磨不开。

  I would feel uncomfortable if it is done this way.

• 他脸上很磨不开。

  He's embarrassed.

• 这件事你得跟他当面谈，没什么磨不开的

  you must speak with him face to face about this matter, there's no need to be afraid of offending him

想不通<方>to not be convinced