Dude is acting on his jealousy about things he IMAGINED that MAY happen in future about his partner who is deeply in love with him in the present.
Idk, he has insecurities and his partner isn’t helping by going on a “date” with someone he knows likes him. That’s the wrong part. But other than that, Kang is fucking up and so did Yi by lying at first. It takes two to stabilize a relationship.
Dude is acting on his jealousy about things he IMAGINED that MAY happen in future about his partner who is deeply in love with him in the present.