Is Seol-a his ex-girlfriend?

 Nav:

This drama isn't exactly following the webtoon so there are chances for a character development.

In the webtoon PJE was actually planning to be serious with his ex girlfriend but here it looks like he is more inquisitive about NB(in an unhealthy way).

For me personally I don't really want her to date Noodle guy because he is too pure and till now she hasn't reciprocated the same feelings. It will be better for her to end up with no one and focus on herself .

I don't think it is a 180 degree flip because he has been expressing that he is getting sick of his own lifestyle.  So while it maybe hard for people to change and they tend to go back and forth, it isn't impossible with a good motivation and NB just might be it. In the webtoon, when he decided to change, he had his ex-girlfriend in his mind and not NB. So i believe the changes they made (including the personality of the ex gf) are pointing towards a redemption arc???
That being said, I do agree they need a time skip with separation to truly believe in their feelings for each other and are not driven by passion alone.

 Genie :

Can  I please have a link to the eng ver of the manga? 

https://www.mangago.me/read-manga/i_know_but/