I have a feeling she will be back especially as Warren is due to leave soon and is up for a dramatic exit.
You saw then fighting in her hotel room on the wedding day after he discovered a gun hidden in her room and realised she was going to try and kill him (she found out he was having an affair with Mandy).
He had his hands round her throat but it was never definite he killed her, just suggested. There was no body so everyone else assumes she ran away.
She was also pregnant at the time, Warren didn't find out until Carmel let it out after the non wedding.