Grouchy from rain? Mine just get annoyed.
1: "She becomes completely helpless in stressful situations."
2: "She is quick to form negative views about things."
#1 there will be a stress multiplier, and #2 means she gets the stress from rain very quickly with short exposures. Moving from roofed to rain repeatedly may be generating a lot of bad thoughts "what? It's still raining? There's no roof here either?". Meanwhile, she lacks the easy stress relievers by being humour deficient, a loner, and not forming friendships. She's also lacking booze, which can't help.
Also, she is impatient and likes a bit of strife, so maybe you can expect some in your future, That is, strife, and patients. Ba-dum-tish.
Turtle the poor wee girl before she goes mad. The new madness is mean, I've got a dwarf with a broken and infected finger, keeps snapping out of it, starting a fight, grabbing some food and booze, throwing some stuff, feeling bad about fighting and throwing stuff, and then dropping into melancholy again for a while. Forgot to turn his labours off, so he kept trying to work and got a bad thought from being unable to complete it with pain. Doh. Building him a nice room for some alone time, which will probably annoy his lover, but such is life.
Anyway: good does not cancel bad of a different category, Super-interested dwarves don't get boredom (or whatever it is) stress, but they get all the other types just fine. You need well-rounded happiness provision, not just an awesome dining room and nice entryway. Including keeping the rain off the grouches, it seems.