You gotta have an understanding that when you are apart you live your own lives, and have a "Don't Ask, Don't Tell" policy.
You two aren't exclusive before she left, right? Use this break to figure out if she is still the "one to beat".
Schedule a weekend away together when she gets back, and pick up where you left off. But in the meanwhile see what else is out there, knowing you have a date in the future. Sounds like she's really into you and needs some reassurance you will be there when she returns...