I think I solved this problem with my most recent playthrough of BG3. My spouse and I each control two characters, switch difficulty to easy, and basically do separate games as individual parties of two. We come together for the big fights or story beats, but mostly she can get up whenever she needs to, go at her own pace, and I explore the parts of the game that are interesting to me.

Honestly, it was the same with me, but I feel like single player is so busted too. Unless you can get a "DnD group" together to truly play focus and get it done, you're stuck with single player. And trying to manage 4-6 characters, and their equipment, and their inventory, in D:OS2 as a single player added dozens of hours to the game in my experience.

BG3 significantly boosted the quality of life with a lot of things. The least of which was getting rid of the "physical armor vs magical armor" aspect.