Uijin didn't really think of himself as clingy. Sure he liked being close with his partner, but that didn't mean he constantly had to be touching whoever he was dating.

When he first met you, he assumed you just didn't like when strangers touched you, which was totally valid of course. But as time went on and the two of you actually started dating, he realized you just weren't that fond of touch from anyone.

He'd notice the way you tensed up when someone went to hug you, or the way you'd move out of the way if someone tried to tap you to get your attention.

Even with Uijin, you weren't too touchy either, even if you did tolerate it more from him than anyone else. He of course realized when you were uncomfortable and didn't touch you if you didn't want contact.

The only times you were ever completely comfortable with contact is when you were the one initiating it, at your own pace.

And so when the two of you were watching a movie and you put your head on his shoulder, he froze. He didn't want you to take it off so he stayed very still, as to not draw attention to your actions and make you uncomfortable.