Yangma shared a note regarding season 3 on Twitter/X and through author note updates/blog announcements after wrapping up season 2. Yangma warned readers that season 3 will involve significantly more emotional angst and painful developments compared to the previous seasons. Particularly surrounding the main characters' past traumas, lingering conflicts and their period of separation.
This was announced soon after season 2 ended, during the hiatus, so the script for season 3 was clearly finished at that point.

Keep in mind that season 3, despite a reunion, does not guarantee their relationship will improve. The author stated that season 3 will be far more painful.
Season 3 is where it all unfolds so prepare your heart~~