How to telll SIRI who my Girlfriend / Brother etc. is

Hi

in the adds you can see how a guy instructs to send a text to his girlfriend by telling siri to do exactly this.

This requires that siri knows which of my contacts is actually my girlfriend. However I could not find a way to so this.

Under the contracts there is just a field where I can define: Wife, Manager and assistant.

Shouldn't there also be other flags like the missing Girlfriend or brother, sister, mother what ever?

Any ideas?

Regards,

David