I agree with Anita.  You should drop any effort on your part to close that space between you and resist the temptation to ask him what’s wrong.  Definitely do not step up your efforts in order to get him to respond to you.  You should continue to resist calling him or emailing him or dropping by his place on the spur of the moment.  Let him make the choice to come to you when he is ready.  If it’s meant to be, things will progress when they should.