While it's good to see a prequel to Unintentional Love Story I'm not completly happy with the story.
First, I don't like clichés like "we are both guys, so it does not matter" ? When can screenwriter just skip such BS.
Second, I am not a fan of cowards, in my eyes both of them are. Kim runs away from his love of his life and Go does not admit his feelings and does not communicate them. Because of the non-communication the end is what it is, even when both understand what they feel.

So I am a bit split If I really like this movie... Production quality was top notch, the acting was also top notch but the story left a bitter taste in my mouth. While not every love story does need a happy end, this end is especially unsatisfying.

Overall it's worth watching even when it will not satisfy everything.

Edit: After some reflection, this story is inconsistent with the original series "Unintentional Love Story", because if you see ULS you will recoginze; a) Did Kim really go to an university in Seoul and if so, what did he study? He should be a doctor in ULS but he owns a coffee shop. b) Go tells Kim, that he always breaks up with his girl which means they never have kissed or had any closer than friends relationsship before. He did that in this story too, he knows his feelings, so he would not have dated a girl again imho. If that would be a famous franchise I would say this story is not canon.