My friend randomly ignores me for long periods of time and I don't know why?

I have this friend who I have been friends with for awhile. We use to be good friends and now a lot of that has changed. We are both girls and I kind of have feelings for her. She knows that and she said she has gotten past that. Sometimes during the year we will talk and be just fine. Other times she will ignore me for no reason and then when I ask her why she didn't include me in her plans she says we weren't talking and that's why I didn't invite you and then threatens to ignore me again. I have been giving her more space now and only texting her occasionally to hang out like once a month. She never puts the effort into texting me. I have made a lot of friends so making new friends isn't a problem for me and a lot of them think she is not worth my time. What should I do?