Constantly stuck between "if what you got is good hold onto it"& "you're young explore"

I'm dating an amazing perfect guy for around 4 months , hes so great but sometimes I think about maybe I should explore my life a little more. I'm going to grad school in a different state and will be leaving him behind after next year. I don't want to give up a guy who's so great and be selfish but sometimes I feel like I could be missing out on something better , maybe ? Idk so lost any advice ?