Dion, apart from private things, in which all of us can only wish the best of luck to Kris, the fact remains he started developing two other iOS apps before (as quite a few Marvin users would put it) "finishing Marvin".
Also, when you visit
www.appstafarian.com, you will see Gerty highlighted at the top of the page, Sift below that, and Marvin is now pushed below them, to the bottom of the list. (And no, it's not a chronological list, because Sift came after Gerty.) The message appears to be clear: Marvin is no longer Kris's top priority.
If that's true, it's a legitimate decision on the part of a software developer, and we must accept that, no matter how regrettable it may be. Like I said, my guess/fear is that Kris finds Marvin "good enough" as it currently is. I mean, look at the crappy iBooks and Kindle e-readers: the gigantic corporations behind them likewise find them "good enough", although they're unbearably lame and threadbare in terms of functionality and user-friendliness.
To me, Marvin has halted about half-way en route to the ideal, professional EPUB reader. Or, to be more generous, it has passed the half-way mark with great flourish, but it's nowhere near the finishing line at this point. Just look at that huge list of bugs, issues and feature requests posted over at
Marvin's GitHub...