A food-delivery website is parting ways with Facebook in a snarky "breakup" letter. And Facebook, like spurned lovers through the ages, is telling the cheeky startup not to let the door hit it on the way out.

Eat24, based in San Bruno, California, lets users enter their address to find restaurants that will deliver to them. They then select a restaurant and order online.

The site has more than 70,000 "likes" on Facebook. But last week, it announced it just wasn't that into the social media giant anymore.

"Dear Facebook, Hey. It's Eat24. Look, we need to talk," read a post on the Eat24 blog. "This isn't easy to say since we've been together so long, but we need to break up. We'd love to say 'It's not you, it's us' but it's totally you. Not to be rude, but you aren't the smart, funny social network we fell in love with several years back. You've changed. A lot."

The problem? Eat24 says Facebook's algorithm that decides which posts users see in their feeds is unfair and rewards page owners who pay to have their posts promoted.

Read - Food app, Facebook 'break up' over promoted posts