I actually find the story of third couple more impressive than the first two
Chowon did some wrong things. Their relationship is different that alpha omega. It's quite unique. The first couple believe it or not were too frustrating and what made them good was the pregnancy deal. I will be honest I was about to drop this manga because of Hye Sung's character if not for the pregnancy. The second couple were quite normal except the alpha beta dynamics. But the third couple r quite unique. What Chowon did was criminal and very wrong. But that aside what happened with Chowon was also unjust but that still doesn't justify what he did. And kungsoo is related to the wronged side so this is quite dramatic and definitely more breathtaking than the first two. And if I tell u the truth, Chowon isn't more frustrating than Hye Sung. Yh he might be more obsessed and extreme but in having shitty personality, Hye Sung isn't or at least wasn't that better either.
But still all these stories combined aren't better than Palace of Bardo. So I think the reason u state definitely isn't the case.
I knew this was coming..............