Structure:

Subject + Verb + 下去
Subject + Verb + 不 + 下去

Meaning:

下去 can be used as a result complement to talk about things continuing or carrying on. Think of it as a figurative way of “keeping the ball rolling” (downhill).
It can be used in a positive way as well as in a negative way.

Examples:

 
1. 这 个 菜 很 难吃 , 我 吃 不 下去。

    Zhè ɡè cài hěn nánchī , wǒ chī bú xiàqu.

    This food is disgusting, I can’t keep eating it.

2. 这个 电影 画面 太 残忍 了，我 看 不 下去了！

    Zhèɡe diànyǐnɡ huàmiàn tài cánrěn le，wǒ kàn bú xiàqule！

    This scene in the movie is too cruel, I can’t keep watching it.

3. 这个 故事 太 无聊 了， 我听不下去了。

    Zhèɡe ɡùshi tài wúliáo le, wǒtīnɡbúxiàqule.

    This story is too boring, I can’t keep listening to it.