It turns out some things are too creepy even for Facebook.

The site has blocked an application that allowed users to get an automated notification when the relationship status of a friend on the site changed. If you can’t see a possible use for that, you’re probably a well-balanced, healthy minded individual.

For the rest of the population, it’s obvious: if there’s somebody you have a romantic interest in that is currently in relationship, the app means you don’t have to keep hitting refresh in the desperate hope of being the first to spot they’ve been dumped and are vulnerable to attention from a “sympathetic” soul.

That’s not me being cynical. That’s the actual reason given for the app (albeit in more delicate terms) by developer Dan Loewenherz: his mother-in-law had spotted a suitable (but attached) potential boyfriend for his sister-in-law and joked that it would be neat to know right away if he came on to the market.

Lowenherz liked the idea so much that he created Breakup Notifier, partly as a technical challenge and partly as a joke. Word of mouth brought 100,000 users; media attention brought another 3.5 million.

Now, though, the app is out of action. Facebook e-mailed Loewenherz to inform him that the app had been removed: not for taste issues, but for the sheer number of requests it was making to Facebook servers. The app checked relationship statuses once a day, which naturally starts to look (in the words of the e-mail) “spammy” when you’ve got almost four million users.

Facebook has since clarified that the blocking of the app was done by an automated system. It’s now manually looking into whether the app is suitable.

Loewnherz will be anxious for it to return to action: he’s said to have been considering a premium option by which users could stalk I mean track two people free of charge, with an additional fee for those who really like keeping their options open.

He’s also reportedly looking into similar services that allow users to track when a Facebook contact removed them from their friends list. That one was already a tough proposition given Facebook specifically bars apps from notifying users when they are “defriended.”