They didn't "ruin" the webtoon; the webtoon still exists.They "ruined" the adaptation.
Everything is different, in the webtoon Sajo Hyun is older than Yeon Wol and he was already the king when her parents died, Hyun's father had died before that incident but he was still the one who ordered the execution. Yeon Wol wanted to avenge Sajo Hyun for murdering her family, although it wasn't his fault because he couldn't dismiss his father's order. He tried to help them but it was the grand vassal Mudal Jin who did that to Yeon Wol's family. When Yeon Wol first met Akhee, she learned that he doesn't have a proper name and she gave him the name Akhee. Later, after becoming the concubine she fell in love with Akhee, she thought Sajo Hyun is cold and didn't like him as much. Later, Akhee sacrificed himself for Yeon Wol to get rid of the evil spirit inside her body (she got possessed as a child and the spirit was concealed inside of her). It was said that Sajo Hyun's and Akhee's personalities would join one day and become one. Also, Yoong isn't evil in the webtoon, he didn't want power. The queen is also better in the webtoon.
When Yeon Wol first met Akhee, she learned that he doesn't have a proper name and she gave him the name Akhee. Later, after becoming the concubine she fell in love with Akhee, she thought Sajo Hyun is cold and didn't like him as much. Later, Akhee sacrificed himself for Yeon Wol to get rid of the evil spirit inside her body (she got possessed as a child and the spirit was concealed inside of her). It was said that Sajo Hyun's and Akhee's personalities would join one day and become one.
Also, Yoong isn't evil in the webtoon, he didn't want power. The queen is also better in the webtoon.