1. Type "What's my IP" into DuckDuckGo.
2. Write down your current IP
3. Turn off your Modem and leave it off overnight 3a. Make sure you turned your modem off and not just your router. Sometimes they're one box, sometimes it's two.
4. Check if your IP changed. If it hasn't then this won't work. 4a. Don't log on to reddit until you do the following.
5. Clear out all your browser cookies, history and other bullshit. Set your privacy settings to strict (this is for Firefox). You can also just use a completely different browser, but still set privacy to strict if you can. 5a. Step 5 is to avoid any sort of lingering cookies or fingerprints that reddit can use to identify you as the same person.
6. Make a new reddit account, don't link any emails you've used on reddit before. You don't need to enter an email at all.
7. Come back and tell us if this worked or not.

Edit: This is advice for your computer, does your GF browse reddit on the phone? If she does, then you may need to take care of that as well.