Why did things have to change now of all times?

it'll be 2 months on the 6th that me and this great girl have been talking ~ in that time some tensions have come up, but we dealt w/them nicely and still found the love that kept us moving forward ~ 5 days ago she upped and changed ~ she's really distant at a time when she usually calls/txts me all the time ~ most of our tensions have been centered around her distrust and her need to test my love by having her friends flirt w/me... trying to see if i'd flirt back ~ b/c of her distrust unecessary tests, i've been taking it slow ~ now it seems she's lost interest ~ she says she's goin through things rite now, but this isn't the first time she's done this ~ any other time she did, she was hanging out w/friends the entire time ~ each time its been an extra day or two added to the disappearance ~ this is the longest time span ~ what do i do? i love her, but what she's doing seems so selfish to me--any thoughts?