Minor quibble...it is confusing to use both Jenny and Jen.  I think all characters in a story should have distinct names.

I like the story, primarily because matches my preferences preferences very well.  It includes:

* Multiple growth scenes.
* Multiple phases of growth.
* Characters who enjoy their growth and want more.
* Erotica

It doesn't bring much to the genre that hasn't been done before.  But to me, that's just fine.  Take some basics, stir them up a bit, and viola, brand new content.  I enjoyed the fact that characters were not teenagers.  I also enjoyed the MMG, to the extent that it enhanced the shared MG experience (while remaining predominantly FMG).  I also liked the husband/wife shared experience part of it.  Finally, I had no issue with the fact that characters let their lust put aside their possible moral quandries.  Sure, maybe some conflict could spice things up, but I'm happy to let the husband/wife partnership put moral issues aside in order to enjoy the moment(s).

Anyhow, looking forward to Part 2.

That's a nice ending, sir. I'm looking forward to a chapter 2 for your young man and his wife!