It is simply lack of clarity and planning regarding  your future.

If you are not able to commit to a person because you feel you cannot see a long term commitment with them or are concerned you might cheat on them, it is better you take time off from the relationship. By trying to maintain a relationship you have no genuine interest or attachment in you are hurting your partner. You cannot force yourself to commit to someone you don't want to. Take time off to figure out why you got into the relationship in the first place and where you see it going. Think about your partner's expectations and how much you can deliver. It is always better and more considerate to terminate a relationship with no future rather than prolong it and hurt someone else as well. If you are not sure, take a step back. Take a hard look at your relationship and only when you are on the same page as your partner, consider continuing with it. Consider professional help if you are feeling hopeless or suicidal.