loss to man, loss to wolf, loss to both
This is wrong, there is only "lose to bandit leader" (although there are two scenes, one losing to him before the wolf dies and another after the wolf dies). The other scene is a collect scene, which means you need to win. The "lose to wolf" is only available through modding.
The game is only frustating if you are unable to learn from your mistakes, like the people who keeps attacking goblin veterans without regard for his buff. The final area is quite hard, but once you have enough talents and know the enemies well, you should consistently beat it on every run.
And of course it's repetitive, it's a roguelite, at least it's nowhere near as repetitive and boring as Darkest Dungeon.
I don't even understand your complaint about the gallery. I hate games that force you to lose for its "special" bit and this game does indeed have about half of its scenes locked behind losses, but ever since version 3, you can surrender up to 4 times without ending your current run, costing you some HP and a permanent debuff to your run (just like the post above mentioned).
The "surrender without ending your run" feature also serves as a "I win button", because you can even skip boss tiles without ending your current run, and you can do it 4 times.
I have fully unlocked the gallery 2 times, once before version 3 (which required me to lose and end my current run for each new lose scene) and again with the surrender feature. I only play this game once every year/couple of years when I am bored.