Maybe this was inevitable since Amazon (s AMZN) acquired book-based social network Goodreads (see disclosure), but Kobo has stopped using the Goodreads API on its website and in its apps, Good E-Reader reports.

That means no more Goodreads ratings and reviews on Kobo book pages. It sounds as if the decision was driven by Kobo, not Goodreads or Amazon: The company’s chief content officer Michael Tamblyn tells Good E-reader that Kobo might re-add the Goodreads API in the future. And back in March when Amazon acquired Goodreads, the companies told me they would leave the Goodreads API open and would not shut off the Kobo feed. (Update: Goodreads confirmed it’s made no changes to its API.)

Nonetheless, the move demonstrates the risk of relying on what is now a competing retailer’s API. At one point, Goodreads actually encountered a similar problem itself: In early 2012, it stopped sourcing its…