All about your comfort zone, sometimes we all like to push the limits and hey why not? We are after all sexual beings and when your tucked in - glass of wine in hand and paperback or kindle in the other and you want to escape from your everyday life; why not make it interesting?
Reading it and writing erotic play are two different things: perhaps you can call on experience in the bedroom or bring your fantasy's to life - sure seems to be going around and has even become box office hits. So why not deep deep into who you are or merely bring your imagination to life. You start with a fantastic meeting and no I don't mean they have to be nice to one another or have even liked each other at the time (misconception is on your side) as a writer what you need to do it make that first meeting "memorable" - and the book will flow - taking your audience where you want them to go!
Tip - if your naughty side wants to come out - but you don't want to share those things with friends and family... well that is just what pen names are for, be creative, love your characters and never stop being positive!