This article from 2 years ago about Joss Whedon brings up some of the same abuse of power issues that we're discussing about Neil Gaiman. Framing these kinds of relationships as "consentual" is problematic.

Joss Whedon Wasn’t Having ‘Affairs’ On The Set Of Buffy, He Was Abusing His Power

‘Who did Joss Whedon have an affair with on Buffy?’ - they weren't affairs, they were an abuse of power. Read more on Grazia.