Why do girls do this?

One minute your on over the moon you think very things going great she’s making all types of promises and saying all this stuff that shouldn’t be taken lightly if not true then the next minute she’s ignoring you out the blue or doesn’t wanna talk to you for whatever reason. Am I the only one who’s experienced this or has anyone else been through this it usually marks the beginning of the end if not the end already.
Why do girls do this?
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