I think he realized he made a mistake, too, maybe, in deciding Hee Bum was dumpable. In fact, I wouldn't be surprised if he thought, "Well, I'll focus on studies now, and Hee Bum will be there when this isn't the priority anymore."
Except: Jumi. She shows up and Yoo Won starts to think Hee Bum may not be waiting around for when Yoo Won is ready to make him part of his life again.
Priorities do change.
But most people know that priorities doesn't mean you drop everything. You just have to portion time/energy to different things at different times in different ratios.
And sometimes we don't know how much people matter until they move away from us. Then we go, "Shit, this hurts. I want them back."
Ooookaaayyy, I admit, Yoo Woon, what you said not totally wrong. I mean, it's the truth, to some extent. He meant that we should set our priorities in life straight, and if something get in the way, then just dump it. But Yoo Woon, we also can't do that because what if along the way, your priorities change and you already dump the important part? What you'll do then? Looking for it on the trash? What if it's already picked up by someone else? See what I mean? ╮(￣▽￣)╭
But, okay, I started to understand Yoo Woon, I guess. Now we just need a backstory so we can understand Yoo Woon all the more. So I can be happy for Yoo Woon and Hee Bum if someday they really get back together. For now though, I won't support Yoo Woon getting back together with Hee Bum.（￣へ￣）