Who initiates the breaks as this indicates a lot.
It seems as if she is torn between you and pursuing life and all that it has to offer. Although she naturally has deep feelings for you and cares about you plenty, you guys are still very young, having been together for four years is a long time in your little lives and she possibly questions whether there is something else out there for her besides you, you know, other opportunities and possibilities. It is understandable that she would want to experiment, date other guys and such, set her free to live her life.
If you are truly 'meant to be together' you will find yourselves back together after many eventful years of experience, at least then you will know you do actually want to be with each other out of choice, only after dating others can this be confirmed.
[SIGPIC][/SIGPIC]
Love is like a merry-go-round: you get all dizzy, and then you feel sick!