It is a very romantic sentiment, but collapsing yourself into a relationship is dangerous. You are cheating you partner and yourself when you lose sight of yourself. It can be tricky, especially when it is new and exciting to go everywhere and do everything that the other does, but a balance must be reached. Set aside time to be by yourself, and to go out with your own group of friends. If there is clear communication, there should be no problem asking for space when you need it. And if you are the one being asked for space, give it freely, because if the relationship is healthy, the person will come back renewed and revived.