so Second leads had to like the leads at the start and then second leads get together?

Not sure if it counts?

1. Kieta Hatsukoi (4 classmates who interact with each other. In the beginning, Sota likes Mio, Mio likes Kousuke, and later Mio likes Hayato if I remember correctly (or Hayato likes Mio first?) Anyway Sota ends up with Kousuke and Mio with Hayato..

 LouM:

so Second leads had to like the leads at the start and then second leads get together?

yes

2. Never Let Me Go - not sure if this counts either, but Neungdiao and Palm are the leads, Ben, their classmate, likes Diao, and Chopper, Diao's cousin likes Ben

 _Shinigami_:

Not sure if it counts?

1. Kieta Hatsukoi (4 classmates who interact with each other. In the beginning, Sota likes Mio, Mio likes Kousuke, and later Mio likes Hayato if I remember correctly (or Hayato likes Mio first?) Anyway Sota ends up with Kousuke and Mio with Hayato..

it does! that's exactly what I'm looking for (love this one) 

 Blkittykat:

2. Never Let Me Go - not sure if this counts either, but Neungdiao and Palm are the leads, Ben, their classmate, likes Diao, and Chopper, Diao's cousin likes Ben

Wow, I watched it this year and don't remember what happened at all. as long as there are sign that the other two [Ben and Chopper] will end up together then it counts~

3. A Little Thing Called First Love. If I'm remembering correctly. 

Liang You Nian < Xia Miao Miao < Lin Kai Tuo < He Xin

In the end Liang You Nian and Xia Miao Miao, Lin Kai Tuo and He Xin

4. Lost you forever 

Tushan Jing ><Xiao Yao < Xiyan Cang Xuan < A Nian

In the end Tushan Jing & Xiao Yao, Xiyan Cang Xuan & A Nian

5. Romance is a Bonus Book - Eun Ho like Dan Yi but well she's clueless. Hae Rin likes Eun Ho and Seo Joon likes Dan Yi too, but eventually Hae Rin and Seo Joon came to like each other and Eun Ho and Dan Yi get their happy ending.

I love how it always sounds so complicated but actually very simple, and the fact that no soul gets hurt too much in the process XD

 puma161:

Wow, I watched it this year and don't remember what happened at all. as long as there are sign that the other two [Ben and Chopper] will end up together then it counts~

I think they ended up together!

 puma161:

10. my liberation notes 

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10 titles where there is a love square (four people, so no one is left alone at the end)

This drama was mentioned above already

 Ahn Sarang:

This drama was mentioned above already

oh sorry. I didn't see (look for it specifically cause it's the perfect example but probably missed it...)

 puma161:

oh sorry. I didn't see (look for it specifically cause it's the perfect example but probably missed it...)

Yes, that's why I mentioned it haha

6. Cinderella and the Four Knights - ML liked SFL, SFL like SML, SML pretended to date FL. FL and ML ended up together, so do SML and SFL

7. History 4 Close to you (Yong Ji and Mu Ren are in love with Xing Si, while LiCheng is still hetero and later on Yong Ji is together with Xing Si and Mu Ren together with LiCheng)

8. Coffee Prince if it counts