Like he knows they've broken up on bad terms so why?

Some of my reasonings:

He's a producer so seeing such great chemistry his produce sparks sparked?

Or he wants them back together? 

I mean I'm sure it's not just for popularity

my theory is he wants them to reunite.

he has been with him since they were a kid and CW's parent even consider him as a son, so he looks after CW a lot. when CW broke up w YS, JW know how hard it was for CW as he notice his suffering, his lacks of sleep etc and even goes to check on him after he met YS again. i notice he also repeats to look at CW's part when he watch the documentary tape.

I watch the actor interview, and it seems JW is not an open character, he tends to hide his feeling and just likes to observe. From what I perceived when reading the manhwa and watching the drama, JW deeply cares for CW but jealous of him for his loving family and his relationship w YS, kinda complicated. I think the documentary is also a way for him to open up to CW or maybe love interest ( i assume it is his female junior at work, not YS, but if it is YS, a lot of viewer might be in rage lol we have had enough of love triangle )

NO SAME I THOUGHT IT WAS THE JUNIOR OMG I THOUGHT I WAS THE ONLY ONE WHO THOUGHT SO

right? he acts kinda different with his junior ( like playful feeling? ) and even invite her to work with him

JW's expression is very hard to read at this point of time.

But I want to believe that he has good intentions. He might want to let them end in a good note. He has seen CW state after the breakup but he might have seen through YS too. He can see all the unhealed wounds and the facades that they still have. It started with a documentary (their whole relationship) and he wanted the documentary to at least settle the past. All for the good of both. 

The only thing that I hope for this drama is to not drag because of a love triangle. I would prefer a negative ending than the prior.

I swear they think we are in love with love triangles but bro WE'RE SICK OF THEM 

 xue er:

Like he knows they've broken up on bad terms so why?

his character is quite simple. Idk why people are complicating his role. He wanted to do that coz it lighted up a spark for him. Thats it. 

imo he saw something in the B roll footage, maybe just how much they used to love each other, idk. But whatever he saw made him want to get them back together. (I'm not entirely convinced he's in love with either of them but I am kind of entertaining the idea that he has secret feelings but wants them to be happy). 

I think he love CW and wants him to move on from her and be happy again. 

I just wish that its not a love triangle, anything but that.

Might be an unpopular theory but it could be that he wants them to sort out any unfinished business that's making them have lingering feelings. Having a clear break up would at least make them move on. Then and only then can he make his moves towards YS. 

 Mawi:

Might be an unpopular theory but it could be that he wants them to sort out any unfinished business that's making them have lingering feelings. Having a clear break up would at least make them move on. Then and only then can he make his moves towards YS. 

Makes sense. 

 Mawi:

Might be an unpopular theory but it could be that he wants them to sort out any unfinished business that's making them have lingering feelings. Having a clear break up would at least make them move on. Then and only then can he make his moves towards YS. 

I agree with this one. He doesn't seem completely innocent. I don't think he'd just be an observer this time as well and make sacrifices for Woong like he has done all along. There's going to be tension between Woong and him at some point when he'd release all the frustration that he's been holding back for all these years.

 Mawi:

Might be an unpopular theory but it could be that he wants them to sort out any unfinished business that's making them have lingering feelings. Having a clear break up would at least make them move on. Then and only then can he make his moves towards YS. 

I was also thinking the same thing! I think he wanted to see if they were truly over each other because he still has lingering feelings for Yeonsu. I don't think he would completely overstep and ask her out knowing Choi Woong still likes Yeonsu but I do see him revealing his feelings at some point.