Great relationship novels

I'm loathe to call them romances 🙂

62 year old male reader here. I read pretty much all genres, be it straight fiction, Sci-Fi, Fantasy suspense, mystery or horror, but the one thing that needs make all of these things interesting are strong characters. And with that comes relationship dynamics. Always fascinating when they're done well.

One of my favourite novels is One Day, by David Nicholls. I just finished his latest, You Are Here, which I also enjoyed, but after finishing it I'm left wishing I had more authors to read that does relationships as well as he does. They are romances that I don't like to consider romances. I like to call them relationship novels.

So, I'm looking for suggestions for other authors like him. I'm not interested in YA at all. I just want really good stories with great characters and their relationships. Family dramas are great. Looking forward to some recs.

Thanks!