OK, you asked for it...
1) The story hits me like this:
HP: We're gathered for a memorial dinner.
Ron: Marry me, babe!
Hermy: Boo hoo!
HP: Me too!
Ginny: [Can't say what I'm thinking about her reaction. Let's just say that her words are a little...clichéd for another emotion...]
Molly: Enough chit chat, why are you two still on your knees? Get up, we have 2 weddings to plan...
It's all *very* **VERY** rushed.
2) Now, your story makes sense to me, mind - these two couples being married a year after book 7, that is. *HOWEVER*, In the epilogue (19 years later, remember), HP & Ginny's first child was born about 2005
http://www.hp-lexicon.info/wizards/potter.html#children
and Ron & Hermy's no earlier than 2006 (Hugo)
http://www.hp-lexicon.info/wizards/weasley.html
*This* means 6 years of marriage without children - certainly possible, but seems unlikely. Of course, 7 years without children seems *extremely* unlikely to me in any case, you'd think they would have married, at the latest, within two years of DH and begun having their first children in the third year...I think all (except maybe Hermy) would have been very interested in starting a family right away. Ron & Ginny are from a large family, and would think it normal to begin the same, and HP would very badly want at least two children so that one would not be alone as he had been.
So, it mainly needs more "fleshing out". First, we don't need to see the whole memorial dinner (probably VV day), but we should have a little more "memorial" to start out with, at least a paragraph's worth.
Second, HP is in the lead role - the "emcee" as it were. I would expect a more mature member of the Order to be Master of Ceremonies and begin the after dinner speech - perhaps me (Arthur), but maybe McGonagall or even Kingsley. A brief introductory speech of one paragraph by an esteemed older member seems a good way to introduce the story. Then, *they* can pass to HP or Ron (see below).
Third, it seems as if Ron and HP are in cahoots with the proposal thing, yet HP defers to Ron. If "cahoots" is what you intended, HP shouldn't be losing his nerve and passing to Ron. I think it would be more fun if Ron and HP didn't know each other had planned to propose - but it's very reasonable that they *would* have told each other.
The main thing that this story needs, though, is more length.
Finally, I'm not sure that this is better, but here's my "HP & Ginny" story
http://www.life-after-harry-potter.com/fanfiction/proposal/page1.html
Warnings:
a) no adult content
b) Draco appears as a villain *again* (he's been "on the lam", evading a prison sentence in Azkaban for his many serious crimes)
c) HP *does* get around to proposing...well, sort of, at the very end
I would be happy to receive scathing criticism, as it helps me to improve my stories.
Jim