Totally agree about writing for one’s partner/lover. Also for some people being told an erotic story during intercourse can be highly stimulating. In one of my former relationships this was so effective that she’d not only cum multiple times during intercourse but would then masturbate multiple times later on while re-living the story I’d told her. And when we were apart I’d send her stories and she’d pleasure herself while reading them over and over again.
Curiously, I’m useless at writing erotica unless I know the person I’m writing for; otherwise I simply have no inspiration whatsoever.