He found someone better after they break up. He is not toxic or anything just heesoo can't give the love he want
*spoilers*
Taku (photographer dude) manipulated Haesoo into dating him. While dating Taku, Haesoo realizes he cannot love Taku because he is still in love with Joowon. Taku senses that Haesoo does not love him but still tries to guilt him into being in a relationship with him. Their relationship comes to a head at Taku's exhibition where Haesoo decides to break up with Taku but Joowon gets in a car crash causing Haesoo to run to his side before ending things with Taku. Joowon and Haesoo confess to each other at the hospital and later that night Haesoo meets up with Taku to break up with him. Taku senses that Haesoo is going to break up with him so he breaks up with Haesoo and tells Haesoo he hopes he feels bad for breaking up with him (basically is toxic till the very end).
last time we see Taku he moved back to Japan (I think?) has become more successful in photography and is holding another exhibition. Taku then says he is dating someone new and that's the last we hear of him.
Well that's the true explanation.
Aw man, I was kind of rooting for him, mostly because the relationship with Joowon seemed toxic at the beginning. I guess what really matters is the Haesoo is happy and now in a healthy relationship! Thanks for the summary!
So I stopped reading this around chapter 30 I think but I just read the last chapter, I love spoiling stories for myself. That ending was actually very surprising (just from what I remember lol). What happened to the photographer dude?