It's tricky. There are 3 ending options:
Be buried, Rejection, and Success.
To succeed, don't think about making her happy. Put yourself in Gu Yi's shoes.
Hint: Everything your brother Liu suggests is wrong.

To get the good ending, just be honest with her answer every question as truthful from the protagonists perspective

follow this pattern 1-2-2-1

Thx

Originally posted by Bourbon:

follow this pattern 1-2-2-1

THANK YOU VERY MUCH

there is another quick direct happy ending with Zheng Ziyan at Chapter 4 if your favorability with her is full or almost full. Choose to meet her instead of Lin Yueqing at Chapter 4.

Originally posted by MasterChiefX9999:

there is another quick direct happy ending with Zheng Ziyan at Chapter 4 if your favorability with her is full or almost full. Choose to meet her instead of Lin Yueqing at Chapter 4.

What do you mean by happyending?

Originally posted by BLACKCREAM:

Originally posted by MasterChiefX9999:

there is another quick direct happy ending with Zheng Ziyan at Chapter 4 if your favorability with her is full or almost full. Choose to meet her instead of Lin Yueqing at Chapter 4.

What do you mean by happyending?

This ending mean Chapter 4 is the ending, no more chapter 5 and so on. you had chosen Zheng Ziyan to be with you, the story end with you will flights with her for travel. This also skip the personal ending timeline with Zheng Ziyan (at Chapter 6) which her interview questions is very difficult to get the all correct answers. At here, only you pass all her questions then you will have the good ending with her.
And you receive the achievement "Off We Sail Tonight" if you get the ending with her at Chapter 4.
Happy/good ending mean you will be with her, other ending could be you are dead, not successful or alone.

1221 works, but why doesn't 1321? recognising the hairstyle is not a lie. Both should work.

Originally posted by nutcrackr:

1221 works, but why doesn't 1321? recognising the hairstyle is not a lie. Both should work.

Good question! Because in Chapter 2 Ziyan's hairstyle was changed but there was no positive response from Gu Yi. So in her opinion the truth is Gu Yi cannot recognize anything related to hairstyle.
That's my understanding for reference.