The two dramas tell realistic stories from the point of view of multiple youthful individuals. Their different experiences with relationships as well as how they mature and discover themselves both mentally and physically are revealed throughout the series.
The changing relationship of the second couple in Adult Trainee reminded me of the leads from FFMY. The dynamic in FFMY seems more sweet and supportive to me while the Adult Trainee dynamic keeps you guessing, but both shows are funny with great chemistry. Adult Trainee is really focused on the character's relationships, while FFMY has a broader message about working towards dreams.