Most Gouldian Finches live between five and eight years in good captive conditions, with exceptional individuals reaching around ten. That is a short life by the standards of parrot keeping and a substantial one by the standards of small passerines, and it means that an owner who takes on a Gouldian is signing up for a relationship that will, in the ordinary course of things, end within a decade. Knowing that in advance makes the final chapter easier to handle well.
Death in this species arrives in two broad patterns, and the difference matters for what an owner can do. The first is a gradual decline over weeks or months, typically driven by chronic disease such as hepatic lipidosis, renal failure, or neoplasia, in which the bird loses condition progressively and there is time to provide supportive care and make considered decisions. The second is sudden death, in which an apparently well bird is found dead with no warning. Sudden loss is common in finches and is frequently the endpoint of a concealed illness rather than a genuinely instantaneous event.
That concealment is worth understanding rather than resenting. Gouldians are small prey animals whose evolutionary strategy is to appear healthy for as long as physiologically possible, because a bird that visibly falters in a wild flock is the bird a predator selects. The consequence in captivity is that visible symptoms often mark a late stage rather than an early one, and that owners who lose a bird suddenly are usually not guilty of inattention. They were watching an animal built to give nothing away.
It also means that the last stage of a Gouldian's life can be genuinely brief once it becomes apparent. A bird that has been quietly compensating may decompensate over a day or two. Thinking through in advance what you would want to do, which veterinarian you would call, and how far you would want to pursue diagnostics in a fifteen-gram animal is not morbid. It is what allows a calm decision at a moment when calm decisions are otherwise hard to reach.