my headcanon for trainees maetbin is definitely ambiguous best friends. they are idols (or well. training to be one) , they cannot exactly date and have it reflect badly on the background searches their future fans will do. they were friends but also something more. lovers but not exactly. they were "friends" who did questionable romantic things together. hanbin used to pet and cuddle matthew to sleep back then as well, they used to go on several late night drives which usually ended in them going to hanbin's place (hanbin also had a solo apartment in seoul after leaving cube so connect the dots yourself), matthew showed up at just jerk wearing hanbin's flannel as well. there's also hanbin calling stargazing a romantic activity and then revealing that he drove matthew to go stargazing together. they were really best friends with severe romantic undertones, all lines blurred you can't even tell where one begins and where the other ends.

i would headcanon that they really really fell for each other After hanbin left cube. it went from friends to something more than friends. atleast in feelings.

so imagine how heartbroken hanbin would've been when matthew told him that he is giving up and will return to canada. matthew will not only be leaving behind his dreams but also hanbin himself. and hanbin didn't want that to unfold at any cost.

NOW severe delulu ahead...heart me out. this is taken straight from hanbin saying "why didn't you kiss :<" at the past lives premiere—

now really give this a listen...
i am telling you hanbin kissed matthew and asked him to stay back for him and try with him one last time together

(runs away \\(//-//)/)