Ok, so looking back at Takuji Yusaku's previous work, it seems like he (she?) isn't opposed to progress characters. This little story was pretty endearing and concise, and I kinda wanted to see more of this couple.
If this is anything to go by, I should be able to expect some definitive progression - albeit slower - from his (her?) more recent and longer work, the Ookii Kouhai manga.