"Oh no, not the same trope again!"
The thiing is, it's not quite the same. What is happening is a mirror to what happened earlier.
First, Minami reveals that she's going abroad. Tsubasa thinks "Oh no, I'm going to lose my precious friend for a long time!" which seems to make him consider just how precious she is. He finds that the answer is "very".
Then she reveals that she's only going away for a few weeks. The relief is palpable.
Now, Tsubasa is returning unexpectedly to Tokyo, just as Minami has had to start thinking about what she really feels about him. This puts her in more or less the same situation she put him, with the added "bonus" that we don't even know if he's coming back.
If the author only wanted to drag out the story and block progress, there are many ways to do that, but they deliberately opted for interruptions that mirrored each other.
This is more than just a way to extend the story. It's a way to put pressure on the characters and make them reevaluate their feelings, and I personally quite like the symmetry.