The guide isn't available for free, in fact, it was being sold for Bitcoins on a deep web marketplace.
Bitcoin is cryptographic currency favoured by criminals as it allows semi-anonymous online transactions.
Such companies offer a wide variety of unmoderated matchmaking services, most of which are profile-based.
Online dating services allow users to become "members" by creating a profile and uploading personal information including (but not limited to) age, gender, sexual orientation, location, and appearance.
Could this dating spam have come from your boyfriend's former adult dating site use?
It's possible, yet more likely that your cell number got thrown into some database somewhere (similar to emailed internet dating scams).
"Can a person get messages from one of these mobile dating things if someone doesn't sign up/or leave that particular cell number?