Great romances of rock rarely are that in real life. I think Pattie Boyd concluded, after her marriage to Eric Clapton, that Eric just wanted what George Harrison had, and once he'd stolen her away from George he lost interest.
Gaiman was always one of those male writers who wanted to be a rock star but never had the charisma or musical talent. That whole image he cultivated, the way he befriended musicians like collecting Pokemon.
Even without the rapey stuff, most male writers are self-aware enough to know how ridiculous it would be for them to pose as pseudo rock stars. I can't imagine George RR Martin striking poses like Gaiman did.