One thing that get me is how uncomfortable Myungsoo is when his exes are flirting with him.
And then you see him trying so hard with Soojin and looking at her so fondly.
And that is how I got invested in the leads.
Also, one thing that's important is all the lady relationships in this drama - also, how diverse the female characters are. You go!
I'm still holding on (false) hopes that Jamie is a transwoman. Who her character based on the manga, Fukunaga, is actually a good trans character who's interesting, whose story isn't focused on merely her gender, and she firmly states that she's a woman 100%. There's not enough good trans characters like that around. Was so disappointed that they didn't keep Fukunaga's character as transwoman in the Japanese version tbh.
And then you see him trying so hard with Soojin and looking at her so fondly.
And that is how I got invested in the leads.
Also, one thing that's important is all the lady relationships in this drama - also, how diverse the female characters are. You go!
Jisang's best friend is so cute. Look at that robot, aww.