Besides identity theft, what else could it be? Maybe there is an innocuous explanation, but it seems reasonable to treat it as identity theft. Have you checked your credit report yet? You may find that the individual who applied with Wayfair also applied for other lines of credit, and they may have been more successful with those other applications.
Beyond checking your report, you may also want to freeze your credit. There was a nice thread on the forum that described how to do so, but I can't remember the title or the name of the user who started it. Hopefully someone will be able to uncover it. I believe it was created shortly after the August 2017 Experian data breach.