Why can i not forget her dreaming about her all the time?

hi im melissa holden and my best friend moved away in year 5(in england thats what we call grade 5) im in year seven(7th grade) and on my sisters account. well we had fellen out 4 two weeks and we made up the last week of year five. And it was the end of the day i hugged her and said i would call 4 her when i come back from my holiday. She said ok x xx. So i went on holiday and when i came back i called 4 her. No one awnserd. i just thought maybe they have gone on holiday. everyday i called for her no sighn. It was the first day of school year six (6th grade) she wasnt there i thought she must of got the wrong week. (her mum was pretty careless and did stuff like tht) but my mum said she might have moved away. i cried 4 weeks. but it is 2 years since then and she wrote me a letter like 2 week after she left. but i keep dreaming she is at my high school (which she isnt ) and i saw her everyday. in my dreams i was sooo happy we were together again. and i wake up happy and look at my ceiling where there is a picture of us and remember help me. i miss her and i keep getting more sad and dissopointed;