Hi Belle!
How long have you two been dating? By private, what do you mean? Do you only have private meetups? If yes, what do these private meetups consist of? Is he just not showing you off to his friends and family, and everything else is fine?
The fact that you are asking the question leads me to believe you are not happy about the situation: is he aware of how you feel? Has he asked you to be exclusive?
If you can answer these questions, I’ll be able to give you a clear and more personalized response.