Hana Yori Dango's Messy Love Dodecahedron
Although Hana Yori Dango's central love polygon is between Tsukasa, Rui and Tsukushi (Dao Ming Si, Hua Tze Lei and Shan Tsai) however we do have more polygonal entries in this one...
Tsukasa gets tangled with Sakurakura (Lee Chen) and later his fiance Shigeru by a forced engagement (Xiao Tze). He basically has every girl after him but he likes Tsukushi for her being her since despite the fact he's a jerk, he's a jerk with a heart of gold. With Shigeru she does eventually give up on Tsukasa because he could never love her thus ending another side of the polygon.
Rui was initially in love with Shizuka (Jing) but due to her supposed proposal by a French guy, he fell for Tsukushi. In the Japanese versions, Rui and Shizuka ended up together. In the Taiwanese version, they eventually split up in Meteor Garden II (maybe Winnie Qian had some other projects...) and he later gets admired by A-Mei, another Taiwanese exclusive.
In the case of Tsukushi aside from Rui, she's also got Kazuya (Qing He) who also likes her. Actually Qing He later dates Sakurakura in the Manga while in Meteor Garden II, he dates a completely original character exclusive to the Taiwanese version named Mimi. In the HYD live version in Japan, Sakurakura later dates Akira which is a radical departure.