Keep in mind that retreat is always an option. That goes for adventurers and creatures. It might feel funny to retreat, but even so it could still be the right thing to do.
There are generally two reasons to consider retreating:
1) the creature or character might die if they don’t
2) the strain of the battle is too overwhelming: they reached their mental limit – they are too scared, too overwhelmed, too tired, or too greedy.
Every creature (or adventurer) has a breaking point. Don’t just ignore when that breaking point is reached. Make sure the creature or character is staying in character and acting appropriately
Sometimes the best way forward is to find another way!