“bújiàn huánghé bù sǐxīn” means that one will not give up until all hope is lost. It is a metaphor that one will never give up until she reaches her goal.
Jiǎ: Tīngshuō tā yòu qù jiàn qián nányǒu le.
A: I have heard that she went to see her ex-boyfriend.
Yǐ: Tā qù le hǎo jǐcì le，zhēnshì bújiàn huánghé bù sǐxīn.
B: She has been there many times. She won’t give up until all hope is lost.
Jiǎ: Wǒzhècì yòu shībài le.
A: I failed again.
Yǐ: Gàosù nǐhěnduō cì le，nǐzhēnshì bújiàn huánghé bù sǐxīn.
B: I have told you so many times. You won’t give up until all hope is lost.