Story is okay, not too special and nothing too problematic.
Acting/production is decent too. Maybe a little awkward at some points of intimacy. It's probably a point from the novel, IDK, but really, rather than the awkward head pats, can't you do hand holding? arm touch? small little gestures? Or at the very least put Wat's arm near Tine's head (shoulder hug, neck hold, back of sofa, anything) at first so it doesn't seem forced.

low point 2: I'm fine if they want to idolize Sarawat, but if they want to dismiss Tine as not-good looking enough compared to Wat, they should have chosen a less handsome actor for him. A cute instead of handsome character might fit better if they want to stick that closely to the novel.
Each Tine and Wat are handsome; both standing together makes amazing visual, so it doesn't make sense for random strangers to fixate on Wat and not even glance at Tine. Not talking about Wat's die hard fans of course, I know seeing your idol makes other people look like trash no matter what.