Re: Two origins on the same pc

@Albino_Napalm  Saves are stored locally on a computer, not in the cloud or on EA servers.  If you were to sign into your Origin account on your girlfriend's PC and play Sims 4, you'd actually be able to open her saves, and your saves would go into the same Sims 4 folder in Documents\Electronic Arts.

An easy way to avoid confusion would be to create a separate Windows user account on the PC that you use when you want to play.  That way, your saves and your girlfriend's are in separate user accounts, each only accessible from that account.