Although at first there may not have been any overt problems between you, over time, as your bond deepened, you both began to realize that there is a fundamental conflict in your needs for independence and for intimacy. These opposing but equally important needs probably can't ever be completely in sync between you two. Your lover likely takes on the role of the more independent partner, the one who requires freedom and alone time, possibly to the detriment of you and of the relationship itself.
You, on the other hand, have probably taken on the role as the needy one, perhaps even the clingy one. These characterizations might not be entirely fair, but they take on weight and dimension as you consider the course of the relationship's past and notice what happens in the future. You probably feel bitter over the fact that your needs aren't being met. You may feel as though you were never completely supported or appreciated, and this is frustrating, to say the least. Your partner, the one who demands and requires freedom, may actually be the one who needs to make the most adjustment if this relationship is going to last. That freedom, guarded so diligently, may end up not being quite as important as togetherness in the relationship. If that's the case -- if you've both decided to continue to preserve the relationship -- much communication and compromise is needed.