You could sit your girlfriend down and do the "advanced configuration" on Windows 10, then she'll understand why Linux is better.
Not sure why we have to "sit anybody down" either...that sounds a bit forceful and unnecessary. Last time I checked, "better" is completely subjective.
But for the record, most people think Windows is better since that's what they've voted for with their dollars. Windows won the desktop war. It's got more users, more apps, more consistency, more stability, more commercial support...more everything. People still fighting for desktop Linux to become popular with regular users are like Hiroo Onoda, the japanese soldier who kept fighting WW2 for 30 years. Good luck with that!
Until that works there is no one Linux desktop - only several different Linux desktops, each with too little traction.
One of them is "Automatically trust WiFi connections my contacts trust", a bunch of others are sending data to Microsoft. It's been a few months since I turned on a new Windows 10 PC but I was completely turned off by the advanced configuration.
The #3 story on HN right now is "Windows 10 in-place upgrades are a severe security risk"
I thought this was a good read the other day https://www.brokenbrowser.com/abusing-of-protocols/
It just seems terrible security wise, the OS itself is spyware.
That is to say, I was excited to be trying out a sexy new Asus Ultrabook with Ubuntu mixed in but didn't care to try after setting it up.