Have you never used a knife like this? I’ve got one that’s been used by people on plates enough that it’s dull - I can press it into my fingers and pull back and forth and it won’t cut me with pretty reasonable pressure. With more pressure if it’s a glancing thing it’ll not take off a knuckle. I’ve just used it so that I could say this but chopping up a cucumber is totally fine and easy. I can’t cut like I can with my actually sharp knife but it’ll cut stuff.
It sounds like she literally has no idea how to use a knife.
Is she doesn’t want a knife which can cut things, Butter ‘knives’ are probably more her speed?
What was she even using the ‘knife’ for before if it couldn’t even cut her? Spreading jelly? Slicing cakes?
Not to be snarky, but it’s possible a couples class which covers things like how to use a knife safely might be a fun and enjoyable way out of this.