A source tells the magazine, ""They are both on the road and have to spend a lot of time apart, which isn't ideal for any couple, let alone a couple trying to plan a wedding."
The two young stars are both touring heavily on separate tours this summer.
Gilbert and Kramer started dating late last summer. Kramer was previously married to Johnathon Schaech for a month in 2010.
Sources say, "No foul play" was involved.