Well, whether it's a good plotline or not can be objective after all, so it's fair. And frankly I don't remember the past seasons clearly enough to support my claim, but as far as I remember, Taesung's entire arc in the past seasons was about learning to be more open to/communicative with Haebom. This specific scene undoes years of his development in one moment and the story apparently treats it as acceptable. I do think some aspects could've been more intriguing if done correctly, but this season is so far just a mix of unmixed vegetables in a bowl. The funeral, the grief, the disappearance, even the relationship fracture are solid dramatic material with no purpose whatsoever.

Bamwoo, drop the drawing pen, I beg you...
This is beyond ridiculous. Besides the fact that this plotline is absolute crap, Taesung would've talked to Haebom instead of sleeping with him, if and I mean IF Haebom ever did+said such a thing.
Author forgot their own characters. It's seriously ridiculous.