This is one of the most sacred things for all men. They extremely respect their private time and their space so if you think that you can enter his life and turn his world upside down, you are deluded.
It is true that they like all those sweet things that the beginning of a relationship brings but once you develop something stable, they will also want to spend some time alone or with their friends.
But don’t be too harsh on them because your own time and your own space are things every individual deserves.