we can never any more wish to be separated than that we can ever imagine a regret that we were ever joined

"Every day we live together adds to the security of my confidence that we can never any more wish to be separated than that we can ever imagine a regret that we were ever joined."

It’s from Mark Twain’s love letter to his wife(https://lettersofnote.com/2013/12/17/always-yours/).
The bolded part is very confusing to me. How can I interpret this?