@Emo-Kingbeat  
Actually the NMM timeline from the season 5 finale shown that Equestria is completely fine in eternal night stuff.  
Makes sense since NMM wanted eternal night so she and her night can be loved as much(if not more) than day, it will be redundant if she ends up causing everyone to suffer and die.

The show should have touched on much more on Celestia’s guilt over what happened to Luna honestly.  
What we got so far isn’t really enough.

@rserp8  
And according to facts, the whole reason behind why Luna fell was all Celestia’s fault to begin with when more and more ponies decided to celebrate the older sibling for raising the sun whereas Luna crafted the nighttime sky with the finesse of Michaelangelo when he painted the ceiling of the Sistine Chapel.
 
And revealed by a recent tweet from Faut herself: Luna did not escape, Celestia simply let her out. This means that Celestia could have resolved this whole mess by herself and apologized directly to Luna and make amends from Day One. Instead Celestia does what she has been good at: she ran away from her problems and distanced herself, crafting the Nightmare Moon persona of her sister to demonize Luna to make herself look good, and when she felt that Luna was never remembered for everything that she once was, only then did Celestia let her free before sending Twilight Sparkle to fix her own problems, and even though Celestia let Luna go from 1000 years on the Moon: Luna wasn’t given much else in the way of choice or freedom to do whatever she wants on her own without getting Celestias’ approval… not even a genuine apology for everything Celestia did was even said to Luna.

Oh no luna

also that was from brother bear

it’s not your falt you where just protecting ponyville

@Emo-Kingbeat  
Dude, she’s sorry for banishing her beloved sister (Those two are a lot closer than you think) to the moon for a thousand years. She only did it because she didn’t want Luna to become a maleovent spirit of terror and she didn’t want her to either hurt herself or others.

It’s not her fault the Elements of Harmony are inconsistant.  
…Actually, they’re consistant based on certain parameters, but we still can’t be sure that she knew that.

@Emo  
She’s sorry for not being able to save her sister, you ass.

She’s very sorry for saving Equestria from a slow death.