Hello dusanofrode,
Thank you for contributing to the Apple Support Communities.
If you can only login to the original user account on your MacBook Pro, it sounds like FileVault has been enabled. This encrypts the startup disk and requires the original user to 'unlock' it before other users can sign into their user accounts. I can see how this might be irritating under the circumstances, and I have some suggestions to verify the situation and help you login to your user account a little quicker.
To see if FileVault is on, log in to your wife's user account and choose Apple menu > System Preferences, click Security & Privacy, then click FileVault. You can find more information about FileVault in Use FileVault to encrypt the startup disk on your Mac.
If FileVault is on, you have two options to be able to login to your user account on startup.
'Enable' your user account to login when the Mac starts up. You can do this from the FileVault preferences (located under Security & Privacy in System Preferences):
Enable Users
Click to allow users to log in at startup and unlock the encrypted information on the Mac. Users that are not enabled need an administrator to log in before they can use the Mac.
From OS X El Capitan: FileVault pane of Security & Privacy preferences
Turn off FileVault:
When you turn off FileVault, encryption is turned off and the contents of your Mac are decrypted. The decrypting could take a while, depending on how much information you have stored. However, you can still use your Mac to do other tasks while the information is being decrypted.
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Choose Apple menu > System Preferences, click Security & Privacy, then click FileVault.
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Click the lock icon 
to unlock it, then enter an administrator name and password.
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Click Turn Off FileVault.
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Click Turn Off Encryption.
From OS X El Capitan: Turn off FileVault encryption
All the best.
