I know it's not really everyone's wish to see the ML dying, but I think the story was justified in itself. There were some questions left unanswered, like why did they breakup in the first place?

Regarding the family finding of ML, the story sets a realisation for him that no matter who is the biological father, he would only find comfort with the person he grew up with, aka his own dad.

Despite having a hard life, never giving up is a big thing while maintaining every situation.
Jae Mi also depicts the important character who plays an important role in ML's life in teaching him the real meaning of love and how true love always gives and lets the person go rather than keeping them to themselves. This realisation helped him achieve the satisfaction he needed all along.

About the family issues they had, later on in the last episodes, ML realised that he had everything right in front of him—Bong, Hyung, Jae Mi, Lacky. All a part of his family now.

Even though the ending is tough for many people to see, it still gives us strength to be okay with not having miracles and living life to the fullest in those situations rather than simply hoping and discouraging ourselves.

The story didn't have many twists or major plot changes or coincidences, but it was enough to keep the audience captivated, and it stuck to the plot, which made it wholesome.

The actors displayed immense emotions, which did not even for a second divert the audience and really touched emotions. Every character was just too good for their role and committed to it very well.

The music was kind of repetitive, and an English-based song didn't really catch up with all the emotions but was somewhat there for the mood. The music could've been better.

Its hard for me to watch this kind of drama, but I'm happy I watched it. Reality-check masterpiece it is.