<human>: Some background, we have had a great relationship so far, right now we're long distance (about 2.5 hr flight) but in August we will both be back at our respective schools and will be a 4 hour car ride away. We both have a year left of school. 

She took a break from school in September 2014 to study abroad and then take an internship from January-August but will be going back after that. I am taking a summer internship close to my home. Our respective homes are a couple of towns over. 

At one point a couple of months ago, she started thinking she was a burden on me. I don't truly know why but I suspect it's because she doesn't have many friends in her area so she relies on me for someone to talk to. However I am not always available so I can't always talk. I do pick up and ask if I can talk to her when I'm done though. 

I love talking to her and we talk almost every night (Skype 0-2 times a week depending in the week. She's not a burden on me at all and no matter how many times I tell her she brings it up again within a few weeks. 

Yesterday though she said she was feeling really upset and didn't really want to talk for a few days. She didn't want to say why though. Later in the day she said she felt like a burden.

We didn't talk at all today but I sent her a couple of text messages. I don't want to bother her too much because she doesn't really want to talk.

She's flying over to me next weekend and I'm flying over to her for the July 4 weekend. After that we don't have anything planned until mid-august. We wanted to, but she's busy almost every weekend until then and she said it would be exhausting. 

My question is, how can I convince her that she's not a burden on me? Just saying it doesn't work and I'm really not sure what I can do from a plane ride away.

Can you summarize the given text in a few sentences?
<bot>: Long Distance Gf is persistent in thinking she's a burden on me because I can't always drop what I'm doing to talk to her (I think that's why anyway). How do I show her she's not?