Ethically, why push forward? I suffer from what one poster above referred to as a "statistical anomaly" of severe, treatment resistant depression, and I relate deeply to the experience of giving up. But perhaps the following metaphor can answer, in part, your question.
When testing different efficacies of medications, psychologists use something called a swim test. They will place rats in a tank of water, and measure for how long they swim until they give up. When the rats have taken certain medications, usually antidepressants or stimulants, they swim for longer periods of time before giving up. To the rat, all seems lost, but they eventually get scooped up from the tank after they stop swimming. To be in that situation is fairly familiar to me, and even though it feels as though I am adrift without any hope in sight, to other people it is clear that I am just in a tank, in need to being scooped up. Perhaps they can see something you cannot in those moments, a way back to dry land exists even if they cannot specify exactly how.
And of course, there is love.