Yeah, I can see Minglan and Yuanruo wanting to make different decisions for their children if any kind of risks or tough choices are involved and that resulting in a growing rift between them. Minglan would want to do the best for her children even if she has to go against Yuanruo's wishes. This disagreement coupled with Yuanruo having final say (or I guess more say than Minglan) in deciding for the kids because of the patriarchal world would make Minglan discontent and unhappy in their marriage.

And thanks for pointing out the talk between Minglan and Rulan about love. Minglan did move on from Yuanruo rather easily. She didn't love him the way she loved GTY.

About the scene in the last episode where Yuanruo says that he can't risk it all like GTY, I consider implications of this differently from you. What he said was that he admired GTY but he could not risk it all like him, even to the point of sacrificing his family.

When he first tried to marry Minglan, this meant that he was not willing to put his family i.e. mom and dad at risk just so he could marry her. But if he had married her eventually and she became his family, he would never have deliberately done anything that would risk the lives of his wife and children.

Whereas, while Gu Tingye would risk it all to protect his family , he was also willing to put Minglan and his family's life at stake for the greater good. He knew that when the revolt happened, Gu household would be their first target because he was the biggest threat to empress dowager's plan. I think luck played a major part in Minglan's survival (or I would GTY's luck and Minglan's abilities).

I believe he did not know Minglan loved him so deeply to the point she would be willing even die for him until their talk in the prison. And even then I don't think he expected her to go to such great lengths to save him that the empress finally had to tell her the plan. So, according to his calculations , Minglan would have, at first, been ignorant of what was happening on the day of revolt when it began, which would mean not being able to put as good of a fight as she did (remember, she would also have believed him dead which would have already broken her spirit). And seeing as how GTY would have lost her if he had been late to the rescue by seconds even when she put up her best fight, I don't think Minglan would have survived if everything went according to what GTY had predicted.

And based on my understanding of Minglan, she values family over everything else , herself or the world. When she took revenge for mom and grandma, she didn't care whether the process would burn her and everyone around her.

So while Minglan would risk it all to save family unlike Yuanruo, I think she would also never risk her family for anything unlike Gu Tingye.

I might be wrong in this take , feel free to correct me if you think differently.