Bacterial labyrinthitis is always secondary to a long standing middle ear infection with constant discharge and from the story that you have told, your partner had an acute sensorineural loss which needed to be treated as an ENT emergency for him to have had any chance of his hearing being retained.
Now the upshot is, that his hearing in the good ear is at a premium and should be treated with "kid gloves"
He has the same chance of losing his hearing, for whatever reason, as anyone else.
See you GP as it may well just be wax.