In the past, there was only one way to publish a book. When I started writing, back in the 1980s, my only option was to write to publishers, pitching my book, and telling them why they should publish it. It took forever and you usually wouldn’t even get a response. When you did, it was more likely than not a rejection anyway. For erotic novels, many publishers won’t go near it because of the adult nature of the content.
Instead, have you looked into self-publishing? Plenty of romance novels have become successful using this method, including 50 Shades of Gray which is one of the most successful works of fiction ever. I suggest you just put the book out there yourself, get a good design, and then use organic and paid marketing to get people interested in it. Get more information on how to self-publish a book by visiting this website.
