Let's see...
The handbook of prolonged manga confessions says that the best thing to do now is have them be interrupted, to sustain the illusion of actual progress, while advancing the plot only by a hair's breadth.
I'm sure not complaining if this actually goes somewhere, though. And I'm probably about as big a fan of slow romances as you're liable to find.
We're already at the point where we're stalling focusing on the side characters because all the aspects of the protagonist's non-relationship have been pretty thoroughly explored, I feel. Surely this author can wrangle another thousand chapters out of them actually going out (or attempting to), if he so chooses...