What if you wrote a novel that ends with the hero giving up on his goal, which he persevered for throughout the story? What phrase would you conclude that novel with?

Well, if I were writing a novel I'd come up with my own words rather than asking someone else to write them.

Also it depends on the hero, the quest and the outcome.

What does “giving up" mean? Is it a good thing? A bad thing? A triumph? A tragedy? A disaster? Why does he give up? Change of mind? Lack of energy? Realisation it's impossible? Thwarted by circumstances or other people? Has a better idea? Achieves his goal and realises he didn't want it?

What's the outcome? Death? Despair? Happiness? Renewed determination?

You're going have different final phrases for:

Jack rides off into the sunset with plain (until she removes her glasses and lets her hair down), librarian Daisy, his perfect match, after having spent the last 15 chapters pursuing sexy supermodel, and all around bitch, Marguerite and taking sweet, loving Daisy for granted.

Bert, a stamp collector, dies at the age of 95 never having found the 1943 New Zealand 2d Red stamp with the Queen facing the wrong way, that he's spent his life searching for.

On his death bed he feels his life has been wasted and he regrets the opportunities for happiness that he passed up in his single-minded quest.

On his death bed he realises that his quest has kept him outgoing and interested in life and that it's a good thing he didn't find it.

Richard returns to the fantasy world he fell into in chapter one and has spent the intervening chapters trying to get away from.

Hunter kills himself:

When his one true love, who he's yearned at for the entire novel, marries another.

When he fails to find the McGuffin in time and the Dark Lord triumphs.

After he kills his daughter's rapist and murderer who has just been acquitted on a technicality.

Steve moves to Takaka to pursue his hobby of wood carving after spending the book living in the rat race in Auckland, when he comes to the realisation that he doesn't actually want to be the CEO or marry the boss's daughter or work 24/7 or live in a city or associate with boring businessmen or spend another hour in Auckland traffic jams or drink $8 flat whites in trendy cafés.

Chris wants to achieve international fame and fortune. He does reasonably well locally and achieves a modest national success but international fame eludes him in spite of his increasingly desperate attempts during which he sacrifices his family, friends, reputation and sanity. He ends up living in a cardboard box begging for money for booze.

Riley wants to join the Royal Ballet Company. He dedicates himself to dance and eventually achieves an audition. Everything is going well when disaster strikes. Riley is determined to try again.