User Profile Question

I have a question regading user profile. Everytime a user gets married and changes their user name in ad, sharepoint does not get updated. My user profile services are running fine and logs shows no error and shows updates are being made. But if change in login id or name in ad nothing gets reflected in Sharepoint. I am running migrate users and sync from ad to update these scenarios. Wasn't user profile sync supposed to do it automatically?

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Adit