Patching of Windows Server 2012 running SQL Server 2014
No, this is backwards. 

Typically, you wanna patch the secondary, let that sit around for a few days, then fail over to it manually. 

Once things are up and running there, run some smoke tests. If all those pass, patch the primary, and fail back during your next maintenance window.


  "Primary gets patched, DBs fail over to Secondary automatically"


You don't have a dev environment to test this stuff on, huh?