This is gonna be really short because they have so little comics together so… I still have to search on more old ones to see if they have any interactions, because from what I've seen they only are shown sharing space except from a few exceptions. So this guide is only gonna go on the comics they have as wives
For a little context, read The Mighty Thor vol.3, specially issues #700 & #701. Kinda optional ig
Now we get to their wedding with Thor vol.5 in issue #3 & #4. I recommend reading the whole series but if you want to skip to their other appearances, read issue #15
They appear in Champions (2019) issue #6 and Strikeforce (2019) issue #8
In The Mighty Valkyries, they are fundamental part of the story, is the best comic of them (also because is the one in which they give them more relevance lol) essential reading basically
Thor vol.6 has an arc centered in Hela were Karnilla appears. From issue #31 to #35 aprox
They make a small but cute appearance in Alligator Loki issue #38 and Alligator Loki: Holiday Special
They appear in Stange Tales (2025) issues #3 & #4
And finally, in Queen in Black: Hela they are stated to be explicitly in love!!!
This one shot forms part of an event which you can search more carefully if you want to, I just read the parts I was interested in (Hela lol)
And that's all for now, thanks for reading!!! I'll maybe make a more extensive guide if they get more content, I'll just keep editing this one until then