In a way, Nora was what pushed Hae Sung moving forward in life-- the mere idea of bumping into her causually around the coffee shop, or having another round of drinks in absolute silence...
These imaginings helped him survive and yet became the very reason that crashed him -- there ain't even a good reason or occasion to say "thank you", because it was all in his head.
He wanted to see her smile in-person because she used to look a bit numb and shy, and he wondered if she's had a pleasant time at school.
But none of it matters now since it was all just a dream of past lives.
Life is not elsewhere.
It's wherever love finds you.
(Haha so cringe. Imma vomit.)