Oh yeah, 5 and 6 are… different. To be clear, by “takes up with” his editor I mean they had an affair.

I hesitate to use the word because afaik Herbert was a widower at the time, but can’t think of a better one that hits the right tone.

Affair is the wrong word:

Affair: a sexual relationship between two people, one or both of whom are married to or in a long-term relationship with someone else. "his wife is having an affair". (Google)

If you’re going to be pedantic, at least be correct:

Websters: “a romantic or passionate attachment typically of limited duration”