Hi I've been playing this for hours now and I absolutely love it. I'm sorry if this has already been suggested but I have an idea and I was thinking that you could have a weather and season system! Maybe?!
To keep the style of the game I don't mean having like a month / time / calendar in the top corner or anything (unless you want to), but rather a slow transaction into the seasons (like every 5- 10 days). Each season has their main difference in the way it looks through the window - like in winter the roofs are covered in snow; in autumn a breeze shows a couple of colorful leave fly past the window randomly once in a while, but nothing hugely major.
With each season there would be possible consequences. Like in summer/autumn the clouds could randomly turn to grey one day and it start raining and this has the possibility of turning it into a storm, which the consequence would be a possible fire (lightning hitting a roof) and or a small flood and you just repair the damages by recruiting workers or whats appropriate to the situation etc. This wouldn't happen every time it did storm - randomly generated obviously, but then that's the point, one year you have no problems then BAM you have to fix everything the year after :D
I hope this was inspirational or at least something that catches your eye to think about. Anyways congrats, this game is really adorable and has amazing charm, I love how you can get so invested in the characters and even feel so many emotions and get conflicted so easily. Keep up the great content !