I feel very disconnected and empty when I’m not with my Girlfriend. Why am I feeling this way? M/20 F/20

Me and my girlfriend have only been dating for a month but we have been hanging out almost everyday, and for the past couple of weeks and we have been having sleepovers almost every night. Whenever we are together everything is good and I feel in love with her but whenever I leave I feel disconnected and very empty inside. I know she likes me a lot and I think we are a great match for each other but I don’t understand why I feel so disconnected from her when I’m not with her. Is this normal? Why do I feel like this and how do I fix it?