A mistake with social media foils a couple's plan for an intimate wedding when thousands of Facebook "friends" unexpectedly flood a small town to celebrate their marriage.

The overall concept could work, but I would make some tweaks.
If the numbers of Facebook friends is greater than 4, then we would not able to know them. So a lot of comedic aspect of having eager misfits turning up would be lost. So why not change it to former lovers who believe that they have been given a second chance?
If you want to keep that great number of friends, then go full tilt. Make them former celebrities or minor royalties who now value their privacy. That announcement creates a media frenzy: everybody chase them for a piece of them. Their former managers want to monetize the moment. Their local friends who were in the dark about their status suddenly try to cash in on their proximity.

I like it. It has instant comic imagery and drama to it. I would change thousands to hundreds for more believability though.

I like it. It has instant comic and dramatic imagery. The believability is a bit off though. Hundreds of facebook friends instead of thousands of facebook friends would be more plausible.