ItsBRN

Her character will mature quickly, her more mature look will match the character.

I didn't get to read everything because of the drama, but apparently they live a life of ups and downs, because of the conflicts involving the palace and the imperial power, but without ever losing their love for each other. They had two sons and a daughter.
As for the end of the main couple, she will die in the end, after he becomes emperor, she dies as an empress some time later, the years took her toll and took her to death, I don't remember how long she stayed as an empress.
The question is how faithful that will be, as they have heard small changes from romance to drama, but there have been.

From there you draw your conclusions, I would say that if the drama is true to the novel, it will be a happy ending, but at the same time bitter.

After all, death is the only certainty of life.