Kinda reverse harem-ish (SPOILERS)

Ling Bu Yi, Lou Yao and Yuan Chen

The King, Cheon Soo, and lowkey Oh Ho Yang.

Xie Liangchen was Xie Xiang and the both of them combined had a few people crushing on them:

Gu Yanzhen and Shen Junshan loved her, Huang Song was in love with Xie Xiang and Gu Qiqi had a crush on Xie Liangchen.

Fuheng, the Emperor, and Yuan Chuan Wang.

All men are main characters, Yuan Chuan Wang being less important than the two others.

Zhu Zhan,  Lu Yun Qi, Cheng Yu, and Young Master Ning. (and me!)

Zhu Zhan and Lu Yun Qi were in love with Chu Jiuling way before the series started and Zhu Zhan gradually fell in love with Jun Jiuling too while Yun Qi's feelings morphed into obsession.

All men are main characters.

Wang Yu, Ta Hwan, Tal Tal, and Dang Ki Se

Eugene, Hui Seong, and Dong Mae.

All men are main characters.

Yuwen Yue, Yan Xun, and Prince Nan Liang (Xiao Ce).

Xie Wei, Yan Ling and Zhang Zhe

Tae Kyung, Shin Woo, and Jeremy. 

All men are main characters.

Yin Xue, Zhan Feng and Yu Zi Han.

All men are main characters.

Chen Yu, Dong Fang Shi and Yun Lang.

The ML and the third ML were great.

Zongzheng Wu You, Fu Chou, and Rong Qi.

Each of their love was bordering on obsession during the entire series.

All men are main characters.

Woo Jin, Yoo Chan, and Kim Hyung Tae.

Gu Ting Ye, Qi Heng, and the doctor (I forgot his name).

13th Prince, 14th Prince, and 4th Prince.

Lu Buwei, Yiren, Prince Jiao, and the Emperor.

Yong Shik, Jong Ryul, and Gyu Tae.

(currently watching it)

Rong Xia, Shi Jin, Prince of Aipuo.

Xie Qi Lin had a crush on her before he broke their engagement (so before the series started).
Shen Yu was faking feelings for her.
Yan Zhen also developed a crush at some point.

kinda?

They all kind of have a crush on her at first but it morphs into a love triangle rather early.