Well, Fifty Shades of Gray has an emotional side to it but I don't like it because in the end the girl WANTS to be abused as long as the MAN did it to her. All she cared for was love it goes something like "what is the pain of a belt compared to the pain of my heart to lose the love of my life" UGH!
If you remove the sex from the book, it has a romanticized notion that there is love at first sight and that love can overcome all of the horrible things that have happened in someone's past. While this is true to some degree, it takes an awful lot of work to overcome it. And in reality it doesn't happen very often.
As for the sex part, after you have been having sex for a few decades with the same person, sometimes you wouldn't mind something a little different to spice things up.
I am not saying everyone, or even a good portion, of the people who read the book partook in any of the scenes, but it may have opened up the conversation for some mild bondage among partners. In order to submit to someone to be blindfolded or tied up, you have to have A LOT of trust in that person.
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