1. I don't think erasing Joon from human memories had anything to do with Ha Ram's become normal. Joon chose to be erased from human memories just so Ha Ram could live/didn't ended up having a suicide after knowing what she did to Joon(pulling those trigger)/her suicide would never happened since the world being reset.
2. I think reasons why Ha Ram could live a normal life/become a normal person comes from Jil dong.
Black/Joon was erased from human memories, but not from the other reaper's memories. So just like Jil dong voiceover in the last ep, while the world was being reset Jil dong stopped Ha Ram's parents accident to happen & take care of Ha Ram till her very last moment as his promised to Black.
Since Ha Ram's father didn't died that day, her father is her mother original husband & not a gream reaper so she won't be having those special eyes thus living a normal life.
3. After the world being reset, Ha Ram ends up marrying Oh Man Soo (they told us the clue implicitly, back then when he nearly died at the cave, he asked Ha Ram to be with him just until the moment he died). Since Oh Man So died earlier than Ha Ram, then she could live in the afterlife with Joon/Black.
4. Ha ram remember Joon/Black existence just right in her last moment before she dies. Jil dong told her all the story about the grim reaper who was erased from human memories & she remember that it was her story with Joon only after she saw their red bracelet, the last gift from Jil dong.
5. Joon is not a gream reaper anymore because he's non existed in this world, thus he only there with her in her last moment because he chose to wait & went to the afterlife with her
Some parts may still confused us though, with this whole reset & roll over thing.
However, given their situation (the writer proposed for 20 ep long but they only allowed for 16 ep & then added another 2ep), while it's indeed rushed, I think it's the best ending they could ever give & I'm satisfied with it.