Tāmen qīfu nà ge xiǎohái, wǒ kàn bu xiàqù jiù chōng guòqù le.
They were bullying the kid — I couldn't stand it and rushed over.
Tips
grammar
Negative potential complement: V不下去 means 'unable to continue V-ing'. Compare 吃不下去 (can't keep eating), 读不下去 (can't get through reading). The positive form 看得下去 exists but is rarer — the pattern almost always appears negatively.
