<human>: Could you distill the essence of the text into 1-3 sentences?

I've been together with my girlfriend for 2 years now and this always comes up as a problem. For the most part, I always hang out with my girlfriend we do stuff, go out to eat, see movies and whatever. I'm so busy with everything I rarely see my friends any more. But when I do, I tell my girlfriend in advance. Hell, I even don't do something with them because I'm doing stuff with her! The thing is, if my plans fall through with my friends I'll ask her if she wants to do something. 

To me I think of it as "Oh poo guess I won't be seeing them tonight. Well I'm dressed, lets see if my girlfriend wants to do something!"

My girlfriend doesn't see it that way. She thinks I'm treating her as my second option, TO EVERYTHING. But I don't! At least I don't think I am. What's baffling, is she does the same thing to me! She goes to lunch with a friend, plan falls through, she asks me where I am to meet up. I've tried talking, but she flat out refuses to see my point because "It's different for her."

Am I missing something here? Am I in the wrong? I just want to get passed this problem.
<bot>: Girlfriend thinks I am making her my second option, I see her all the time and blow off other plans for her sometimes. I don't understand why she thinks that.