Well, this was disturbing. My heart plunged into my stomach after
reading "It's been ten years now...."
I almost wish you'd left it at that. That would have been a powerful
story; as you said, just because they profess love for each other
doesn't mean it's a happy ending. Ranma doesn't have to die, but his
absence without any communication is just the same, and the agony of not
knowing is worse than the agony of mourning.
It would be interesting to expand this a little, have flashes of Akane
through the years, graduating, attending her sister's weddings, learning
to take care of the house after her sisters leave, etc. In each,
she goes to answer the door, hoping it's Ranma, but it never is.
Through each her hope diminishes and her despair grows. If you do
decide to keep the happy ending, then Ranma at the door in the final
scene will have more of an impact - as it was, the reader knew that it
*had* to be Ranma at the door, it wouldn't make sense for it to be
anyone else.
I loved the bit about the children and how they represented all that
Akane had given up by falling in love with Ranma.
Let's hope you hear more boring lectures, I'd love to see this fleshed
out a little. :)