The female character cried multiple times in each episode. It is heartache and her character is so 50-50. My wife would comment how can a female be that stupid and unfeeling towrds her actions involving the two men. That was why she was crying in the first place.
Character development of this story comes from reading between what is happening but it leaves to much imagination for the viewer to have a factual basis of the development There were enough instances through the series that one had to assume the prior history by what was involved with others. I wondered how the rich father would entrust such decisions to the son who has constantly demonstrated failure time and again. Especially to be so easily maneuvered into being such an easy mark.
The other male character was from a poor and rough working background. He succeeded well. He'd shown forethought into planning his rise that in the end it was a contrived way to cut it. To constantly beat on the rich family was another tiresome playout. The rich son had told him he's trash and he'd continue to be trash. So yeah, he's going to make the rich family his target for retribution.
Summary and ending: [spoiler]The poor character Kang Young-gul worked hard and didn't find happiness. The rich character Jung Jae-hyuk failed in business but got the girl through deceit. Each character here was manipulated and that ongoing premise just wears thin.
Young-gul is shot while drunk in the wading pool of his luxo NY apartment. (Having milked the rich family one last time for $150 million/150 billion won) To add shock to viewers, he's talking with the girl he loved at the same time he's killed. Gun fire is heard on her end but she keeps talking as if nothing happens.[/spoiler]