Responses
I think their relationship is not childish, it's just that the ml still don't know how to deal with stuff like that. And the fact that there relationship is still new, and they both hardly know each other. He grew to be an awkward person, but the fact that he confessed that he's jealous from one of the chapter shows he's slowly opening up to the uke and communicating his feeling and concern.
Are you a child? I can expect this from a 14-year-old boy. Honestly, if this love story makes you so insecure, maybe there’s something wrong. Zero communication from both. And now Jeongmin can’t even talk to another person? This jealousy is not healthy. I’m sorry but I find this relationship very childish.