Just let me say this how do you know that you are in a relationship. If you are seeing someone for a month. And you spend most of your time with them then you are in a relationship. Having sex with someone more than once then you are in a sexual relationship. Unless it is agreed that it is just sex in the begin. And then that doesn't last cause someone catches feelings. No matter what you do if you don't want to be in a relationship just say so and let it be.