Does anyone know of any beginner guides to playing the guitar and keyboard that match, so you and a partner could learn on your own (one playing guitar and one playing keyboard) and play the same songs together as you learn?
No, but it’s a neat idea.
Finally, someone answered me! Thank you.
I guess I will just have to go on Amazon and order some beginner books even if they don’t match. 
You should find some that have similar songs. My reply above shouldn’t be taken to mean there aren’t any such books, only that I don’t know of any.
Meh, I couldn’t find any. Yep, we can just do the separate beginner books I just ordered, then start playing some simple songs together. I feel so sorry for the neighbors haha.
Which one are you?
You don’t mention what style of guitar so here are two choices:
Free PDFs of classical guitar and piano duets – most are too difficult for absolute beginners but some (look for the word “facile” in the title) are suited for those with perhaps six months to a year of experience.
http://www.classicalguitardelcamp.com/viewtopic.php?f=7&t=18186
And a book on Amazon aimed at beginners, not necessarily for classical guitar.
And here might be exactly what you need – a youtube video of a very simple beginner piece followed by a link to a printable version of the sheet music.
Easy Piano Guitar Duet - Falling Slowly
BTW – It’s a great a idea to learn to play with other people.