Firstly: i used to love etihad and still think its a great airline.
However, i had recently recurring problems with their website. Sometimes web check-in could not be completed, most recently a flight booking with miles was interrupted. Money was deducted, but ticket wasn’t issued, which cost me around 30 (!) min on the phone with the etihad office.
Plus: for this particular flight AUH-FRA every single seat selection would have incurred extra fees, not only the exit row or other “preferred” seats!! I find this a bit too much.