I'm not close to Gaiman or the fandom or the story, at all ... but I did manage to pickup on some of the whisper network through mastodon, where I read a couple of posts or blog posts by people who seemed to be close to the fandom and even be friends with him (in one case). The vibe was very much he's likely a womanising guy and has been his whole life and likely has standards "below" what most would consider normal. There also seemed to be a bit of introspection about how much the fandom around him was kinda culty and that that clearly enabled whatever he did, as a common enough pattern seemed to be that someone would go through something unseemly, but because it was Gaiman and all their friends were fans, they presumed it was them or their fault and never wanted to open up about it.

Like I said though, this is essentially gossip, so don't take it seriously or anything (also I don't have any links or anything).