Notes

Pink diamond/Rose Quartz didn't reform because she is dead. There are various points across the series, but especially this episode that makes it clear this is the case.

The biggest answer lies when stevens gem reformed. Instead of reforming into Pink Diamond/rose quartz, it formed into steven. And the gem was an emotionless husk, which only acted to return to Steven's core body, as it knew Steven was dying. When grilled about where pink diamond was; it literally booms "SHE'S GONE", which means what it means.

So, it would be evident that Pink Diamond's conciousness no longer exists in stevens gem. Rose Quartz DID say that "The two of us can't both exist" in the episode 'lion straight to video'. In my opinion, it looks like when she brought steven into being his conciousness overwrote hers and she just ceased to be.

A spiritual death.

But not a physical one.

Her body is was what 'Pink Steven' was. Her body still exists(after all, her gem is her body), but it's no longer driven by her own conciousness. It was just driven by steven's own surrvival instincts. This would also be why steven can see her memories; her body and her memories still exist- but her soul is gone.

When Steven embraced Pink Steven, it bursts into emotion- I really believe thats because Steven was accepting the part of himself that he had been internally rejecting(her). He was deeply ashamed of what his gem represented, and at times, hated it. So that was why the gem had absolutely no emotions at all. But when he embraced it, the gem truly felt and became 'himself' for what had probably been the first time.

White diamond pointed out that steven had been suspicious this entire time that he might not really be 'Steven' but Pink Diamond his whole life. But at the end of the episode; Steven reiterates with relief that he was 'himself the whole time', which means that he is now fully aware and accepts that his mother's conciousness is completely gone and was never there to begin with.

She remains with him only in body, and the promise she made to him that every moment he loves being himself, that it is her and her love for him. And this episode seemingly revealed to us that she really only meant that promise in a metaphorical sense, not a literal one.

https://steven-universe.fandom.com/wiki/Thread:933659