Memoirs of Hadrian by Marguerite Yourcenar. Arguably the greatest queer novel of all time. The love affair between Hadrian and Antinous is both wonderful and disturbing. It's pitch perfect, not for a moment does one think it is not written by Hadrian himself.
Yourcenar was a Lesbian, partnered with Grace Flick, yet she had a habit of falling in love with gay men. All her novels, that I know of, have a gay man as the main protagonist.
The Twyborn Affair by Patrick White. One of the greatest mysteries to me is how Patrick White is such a relative unknown in this country, particularly among queers. This was an openly gay man who won the Nobel Prize for literature for crying out loud.
I read The Twyborn Affair almost 30 years ago. Everything is a blur from back then so I can’t remember how I got to it but great to see it on your list.