whats really going on with women

ok very briefly..me and my ex broke up about 4 months ago...well long story short she left me because i just didnt feel like i loved her and never said though she cried and cried to me that she loved me and too not let her go. well we talked for a few weeks after. not much talk just small talk. then we stopped for a few weeks. i did alot of thinking and realized how much she meant to me. its been about 2 months after now. well when i went to contact her i had found out that she blocked me from all interent communication and even changed her phone number. i tried and tried for about a month and was finaliiy able to get ahold of her and asked her if she wanted to talk about things. she told me know leave me alone i dont want anything to do with you....i dont understand...we never even talked about anything...well anyway she pretty much dropped me from her life at the drop of a hat and i most recently heard she was back with her ex...so my question is..is she on the rebound and just looking for someone to be with or are we truly over with?...because i know girls like that and they are are just not able to be alone...and if so why do girls do this? are they trying to get over it. or are they just so needy...thank you for any advice opinions or comments