Is this person really a friend of mine(details)?

I have this friend. We’ve been friends for a year, going in the same class. She’s one of the people in my life that I can have the must fun with. We’ve seen each other every day in school and we’ve been spending a lot of time outside of school together. I’ve also told her some personal things. Now, we have vacation and I’ve tried to contact her for more than a week. We decided to go out one day, but when that day came she didn’t pick up her phone, so it didn’t happen. I’ve been sending her text messages about some pratical stuff and she didn’t reply for 5 days. Today she finally replied, but it was very short and cold. I asked her if she wanted to hang out tomorrow, no answer.

I know, this may sound really lame. I just don’t understand it. If a friend acted this way towards you, what would you think?