It's usually 5-6 weeks per update. Last update was a bit of an exception since I decided to keep going with the writing for v0.43 (the upcoming update) instead of making it the usual length, and with the way I work (I finish writing for the very next update before rendering and releasing the current update at the time), that ended up extending the development time for v0.42. :)
I do enjoy writing quite a lot, yeah. The way I think of CH reflects this pretty well, I'd say: In my eyes, the game isn't a porn game, first and foremost, but rather a romance visual novel with supernatural elements.
However, I do think that every good romance novel should include sexual themes, seeing as sex is a normal part of real life romance (with exceptions, of course). So, writing about love but ignoring sex seems kind of silly to me. Hence my making CH into an adult visual novel with the focus on the "visual novel" part, rather than the "adult" part.
But fret not, there will be a good amount of adult content in the game, too.