Excellent first release! And developed by a married couple, what a treat. The future looks very bright for this game.
Here's a quick and dirty scetch of what I would change about the UI. The blocky floating dialogue box and the sans-serif font doesn't fit the rest, imo. Something that really struck me as "off". Maybe make the box a bit more transparent and smaller, too.
In the crystal ball I've also noticed inconsistent fonts. I strongly suggest you choose one font family and stick with it throughout all texts. Also keeep at least the ratios of headline to text consistent, and only use as many different sizes as absolutely necessary. Many different fonts at many different sizes all over the place doesn't look good.
The animation of the Maple scene was decent, but leaves room for improvement. If you check out
this fan art thread, some have been using a neural network to smoothen out low framerate animations and the results are quite stunning.
I feel the scene of Myrtle in the water was too easy for a full nude reveal, like a missed opportunity for more content.
Off the top of my head: Maybe when the MC dives towards her he sees a shadow under water behind her and panics, swallowing water and rushing to the surface, then getting chased away by an angry Myrtle. Later, when he again tries to spy on her, he sees the creature again, revealed to be a hot mermaid from an underwater kingdom. Just a thought.
And as a final remark: I'm missing a bit of body variety. Not that I don't like the models, but variety is the spice of adult games. Will we get a voluptuous miller's wife and such?