
well its because of 'calmness before the storm' jin woo can't predict what's going to happen once the portal was open so i guess he wanted to enjoy it with a someone whose he's interested at (but lmao when i read the novel i was so shook too since the romance came from out of nowhere) and yeah maybe he kind of want to spend time with her

Dude he literally said that he wants to visit the place where a certain portal sprout that took his father from them, and considering how big that new portal up there, the best time to visit that place is right now, it's not labeled as a date actually, jinwoo never said that it was, he probably just wanted a companion, our man have feelings too.
A sudden date... Isn't the portal a chaos? Is it the day before the portal appeared or what? Why is it like nothing happened? Why did Jin Woo went there with Cha Hae In, not with that one of the guy his friend (I don't remember the name), right? He can go with him.. Why her tho? Author is something