This is tricky for me to talk about without spoiling a whole lot. In many ways, Celestia is portrayed in the movie as Twilight’s surrogate mother. Its clear that she cares deeply for Twilight not only as her student, but as her best friend.

Keep in mind that Celestia has had to live with a thousand years of regret due to what happened with Luna. Its thanks to Twilight that Celestia, in some ways, found the light to start anew. So she has a strong connection to Twilight because Twilight gave her something she felt she had lost. So imagine the emotions that Celestia feels when Twilight is gone. She feels like she’s lost another person she loves.

But over the course of the film, there is a point where Celestia realizes that Twilight is growing up and rather than wanting to have Twilight be someone she isn’t capable of being, she urges Twilight to choose who she wants to be and never judges her for the choice she makes.