Let me guess

Hey now, abuse is too strong of a word, he never laid a hand on her or insulted, used or manipulated her in anyway.

HOWEVER, the word I believe you are looking for is neglect, he never treated her in the way a wife should be treated.

But the guy got his body disfigured, saw himself as hideous monster, who did not deserve another human touch, suffered from severe PTSD after the war, and grieving losing all of his family.

now that’s not an excuse for the years she suffered in loneliness, but will you be able to open your heart after going through what he had been through?

Besides Madeline is not completely blameless in their marriage ending up in tragedy.

And Compered to things like for example Abandoned Empress this like a wake in the park, and more realistic.

The fact that their relationship in past actually got better, but it worsened because someone else.

The ml didn't abuse flThis ml aint one of those trashy ml.

This guy literally fought in war where he saw his friends getting burned to crisp and himself got burned and injuredThis man was traumatized by war. THEN was tortured by the doctor.

Could be a spoiler.
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Yup, as the 3 users before me mentioned, it's not "Abandoned Empress". Here's the thing, abuse doesn't not have to be physical, it can also be mental. The worn down type.
The premise is WW1. The thing is, ml has war PTSD. Then comes self doubt, fear, low confidence from it. A spoiler, he had a big family, but lost them all within just 1-3 years. Which is another kind of pain. Survivors's guilt eats away at a person. So, he left FL to be in her world, thinking it's best for her.
Fortunately, she took action, eventually, after a long time. So, ml took her hands & started to get better. But alas! PTSD!
So, ml decides to get treatment for himself & for FL. This is where things go boo boo. & the psychotherapy then... We all make fun of & scare people of that past. But, for those people of that time it was the latest, upgraded & better option. So... Yeah, that's where their relationship go downhill.

That's still not abuse, that's being a neglectful and terrible husband. Honestly, I would consider making him go through electroshock """therapy""" more abusive than anything he ever did. I wouldn't say the FL is terrible for prioritising her feelings, that's valid, but don't expect a traumatised person not to, I dont know, act traumatised.