Someone turned us on to Trying Out Marriage With My Female Friend by Usui Shio (aka Onna Tomodachi to Kekkon Shitemita) and it's extremely adorable!
Minor content warning for hospitalization (spoilers inside for those who wish to skip it)
In Chapter 7 ("It's alright, I can endure this"), Ruriko has pain of increasing intensity, which she downplays because she doesn't want to ruin Kurumi's day ... but this means that it is only when Kurumi gets home that she learns her wife is in the hospital. (This is thanks to the couple's mutual friend Kuroda, who realizes upon calling that Ruriko is very sick and takes her.)
Ruriko's pain turns out to be appendicitis - fortunately a minor case, but she has to be on antibiotics through an IV for three or four days, time which is skipped over fairly quickly. The main thing that occurs here is Kurumi being distressed that Ruriko didn't tell her ("that ... that makes it seem like we're nothing more than friends...") and telling Ruriko, "There's nothing more important to me than you, Ruriko" when explaining that Ruriko should have told her and it wouldn't've been a bother.
(Instead of being able to verbally acknowledge this, Ruriko notices Kurumi's wet hair and tells her that she shouldn't forget her umbrella - "I don't want you to catch a cold." Kurumi accepts this as just the kind of person Ruriko is.)
Ruriko is discharged on page 00074, near the end of Chapter 8 ("What's important to me").
(Also, content warning for food - it's a recurring thing throughout - and occasional alcohol.)
This is slice-of-life in the most lovingly mundane form: the protagonists navigate chores, purchases, and differing dispositions, and the feelings and questions that spill out from these day-to-day things.
...but they also deal quite directly with amatonormativity. Their marriage does not fit the cultural model of romance and sex that surrounds them, but it also does not fit the model of "just friends" that they initially assumed it would. They care quite intensely about each other, are desirous of each other's company, and do their best to support each other through struggles small and great. Their approach to the whole affair feels much in the vein of relationship anarchy: dissecting their feelings and making decisions based on what works for each of them, finding where their joys lie and celebrating that in the face of the obliviousness of others, and talking to each other.
I don't know if their relationship as of now is more queerplatonic or ace romantic, and I don't know if the author plans to remain in this space for the rest of the story's run or to portray its metamorphosis into something else. But I do know their relationship is healthy, and nuturing, and sweet.
It's currently serializing in Japanese - Chapter 22 came out this month, looks like.