While the pain of your girlfriend being away for long periods of time might seem unbearable, constant sadness can consume you if you let it and can even make her feel guilty for not being there. Instead of focusing on how much you miss your girlfriend, focus on the positive. Find ways to communicate long-distance and keep yourself busy with activities that will provide a healthy distraction, bring you comfort and get you excited about seeing her again.
If you can, communicate with your girlfriend while she is away; this can help make the separation easier. Talk to your girlfriend on the phone or via live video chat at least once a day if possible. Even though it's not the same as her physically being with you, seeing her expressions and her smile on video chat comes pretty close. If you are in a situation in which you cannot phone or video chat with your girlfriend regularly, such as if she is on a tour of duty in the military, write her letters. Let her know what you are up to and how much you miss her. Send her care packages with treats she'll love and cute gifts that will remind her of you.
Instead of lying around feeling sad about your girlfriend all day, distract yourself from missing her. Hang out with your friends more. Go to the sports bar to catch a game and be around jovial folks. Take up a new hobby, perhaps something you have always wanted to try or learn but have never had time for. Whether you choose rock climbing or joining a local basketball league, immerse yourself in your new hobby to give yourself something to look forward to besides seeing your girlfriend again.
Do What She Would Do
Sometimes doing things that you would normally do with your girlfriend when she is around can bring you comfort and make you feel her presence in a way. Challenge yourself to recreate that amazing banana bread she makes for you, for example. Go see that chick flick she would have dragged you to so you can talk about it on the phone. Check on her great-grandmother if she used to take you with her on visits. Volunteer at the animal shelter she is passionate about. She'll be so proud to know that you are investing yourself in the things that she cares about.
Make Reunion Plans
Making plans for when your girlfriend returns, or for the next time you will see her, can make the time go faster and distract you from feeling sad. Think about something she has always wanted to do and make plans to make it happen. For example, if your girlfriend has always wanted to visit New York City, make plans to whisk her away for a whirlwind big-city weekend that includes staying at a swanky hotel, visiting famous sights and sampling pizza in every borough. If she's coming home from a grueling trip, plan relaxing activities for her, such as an in-home massage or a quiet bed and breakfast for a weekend.