I think it’s okay to say to someone if you’ve been with them for a little bit but I would absolutely rephrase the way you’re saying it. Ex: I really like (literally) sleeping with people and might say something like “I really like when we are able to sleep together, it makes me feel close with you” rather than “if we are in a relationship, it’s an expectation I have that my partner will sleep with me if they are comfortable with it”.