Let him go if he comes back to you it will be wonderful if not your relationship was not meant to be Get over it and move on There's lots of men in the world, you'll find the right one, be patient
Whenever someone in a relationship tells you they need space, there is always a chance that you will lose them. This is just a chance you have to take. If it is meant to be, he will come back to you b/c he will realize how much he misses you when you give him his "space" There is really nothing you can do to make sure he won't leave..just be nice to him, treat him good and respect that he needs his space right now.
Are you two having a lot of problems? Maybe you are just spending too much time together. If he really loves and cares about you then he will come back. A really good relationship has to go both ways and if he doesn't come back then you are probably better off with out him. Good luck to you.
Just let him cool down soon he'll find out he's nothing' without you it might take a while