Literally one of them already has two gay parents. STFU, its a shitty story with a shitty ending. There are a ton of comphet stories, you don't have to defend every single one with the dumb ass "Based on real life" when getting married and having children is at the lowest rates in Asian and Western countries. No one gives a shit, therefore these comphet stories have lost all meaning. Especially one like this with the most welcoming starting premise to a gay relationship in broader society. It's like having a comphet story in modern France, it's unrealistic and based solely on shitty writers sticking to old and tired tropes. And being a bad writer and not knowing how to use those tropes correctly certainly doesn't help.
Didn't Mumu say it herself? She saw her own gay parents hide the fact that they're gay from a majority of the people around them. She watched them have basically no contact with the families that they had just to be together. She watched her parents continue to keep hiding because they were afraid that their daughter will get ostracized by everyone else.
And on top of all that, Mumu had to watch her girlfriend be pressured by an ignorant yet caring single mother to settle down and find what society deemed to be a happy family and a stable future. She was afraid that the bad stuff that happened to her and her parents will happen to Wanwan because they were a gay couple.
This story isn't shitty, it's their situation that's shitty. Considering the theme, you can say that this story is uncomfortable to read. But that's the point. It's supposed to make you feel uncomfortable about both MC's bad decisions.
A good story isn't decided by how happy it makes you feel but by how well it can make you think of and feel about the situations the characters are in --
both good AND bad.
You're telling me not to defend this "with the dumb ass 'Based on real life'" argument but please do give things a little bit more thought.
You said it yourself,
"having a comphet story in modern France is unrealistic".
Spend just a tiny bit more time reading and understanding why the story was written the way it is. Don't let what you think is common sense stop you from understanding another's reality.
You're forgetting that this story was written by a Chinese author and started and ended between mid 00's to mid-late 10's and is set in China. Things are a completely different case over here in many East and South East Asian countries (especially if the country's culture has a stubborn outlook on maintaining certain traditions and/or beliefs).
I wish it wasn't the case but, we're still behind on the times when compared to the West. Maybe if you check the internet side of things, a lot of people are more accepting. But it's a lot harsher once you go offline. It's not as bad as it was a decade ago but we still get stares when walking hand-in-hand with a partner of the same sex. Even today, relatives will talk behind our backs and will comment on why we haven't gotten married yet or why we don't have kids yet. I doubt people from the West have an equivalent for this type of societal pressure. You guys value individuality and independence just as much as we value relationships and community.
This isn't a comphet set in modern France. It's a story set in a place that just barely started acknowledging gay people.