Aw why couldn't they reveal their relationship.

i know!! i thought that was what he was talking about on the phone

Same here!

I honestly think it was for time's sake. There's only so much they can fit into each episode, and the issue with Minhyeok's dad was obviously the priority for this mini-arc. Introducing that right then and there would be too much to unpack mid-family gathering, and the news would end up as a side note