If you spend all your time apart from him with your phone in your clenched fingers, waiting for it to vibrate with his name, put the phone down. This isn’t ideal for either of you. Of course, you love talking to him, but you have to leave some energy for the rest of your life. Don’t be half-invested in a conversation with your friend because you’ve got one eye on the phone.
It's like with dogs or children — you stick to your guns and you politely, patiently repeat the boundaries until they respect them. He gets it or he gets lost. Period. If you truly start to follow this theory, he'll feel how serious you are about being respected, and if he's at all serious about you, he'll get aboard the good boy train very fast. He'll know that if he doesn't, he'll be left at the station!