The beach battle hurts me in a lot of ways, but especially because it’s likely the first time Diana has ever seen someone die. I was thinking about how slow she is to really react on the beach, while the other amazons have no problem charging right in, and I think that’s the reason. As skilled as she is, she’s never seen battle. She’s never seen death.
And every scene after that with the same sort of horror - her seeing injured soldiers come back from the front, the attacks on innocent people in the town - is the first of its kind she’s ever seen. She’s learning all the worst things about the world very quickly, and it hurts to watch.
(I think Steve feels the same way. When he sees her shock and horror on the front, it makes the whole thing fresh for him after so long being desensitized. Diana brings out the humanity in her friends, in both good and painful ways.)