The female lead's character was cruel and a liar. The male lead's character continued to pursue a women who continued to treat him in such fashion, and he never thought, "hey, perhaps I can find someone who treats me a bit better." The end is about them 'reminiscing' about what could have been, in some fantasy world which never could or would have happened because the female lead liked to play games.
I've read some of the reviews, and comments about the writer, who may have been experiencing personal life issues that resulted in this story, but he actually did have a point that he was trying to make, although he could have done a much better job making it. Since I saw the show to the end, it's the end where his 'point' is made. He thinks people miss out because of a lack of 'going' for it, or a failure to communicate, or a failure to be decisive. Whatever. What I took from it is that his female lead is just cruel and not good enough for the male lead. I'm sure that wasn't his point. As some have pointed out, at least a few of us didn't even want them getting together because the relationship was toxic. There was evidence that the female lead was mentally unbalanced--showing narcistic, compulsive lying, and an inability to empathize. Why the male lead would want to continue to put his life on hold for such a person, I've no idea.