How to show the guy you're not easy to get?

So me and this guy have been dating for a month and we had sex on the fifth date. and almost every time after that we have had sex too on other dates. Now I notice he just kinda expects it and I want to come across as not easily to get. I love sex of course but I just don't wanna come across as that girl that's not special that he has to not work for. So what can I do to turn the tables around to show him that I'm not that easy and he has to work harder for me? Because I heard guys appreciate girls more the harder they have to work at it to be or get with the girl. So what can I do?
How to show the guy you're not easy to get?
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