My other half isn't much of a gamer but she has my old low end laptop and wants a co-op game that we can play together. We've previously played Minecraft together but nothing else, she just wants something we can play together.
Any good recommendations that are cheap and not graphic intensive?
Unsurprisingly, Terraria has already been mentioned, but I'll throw my endorsement behind it too. Especially since you've already played Minecraft, so it's a great jumping off point.
Not coop, but maybe some racing games, such as Sonic & All-Stars Racing Transformed?
Don't Starve, or other 2D survivalist games.
If you like turn-based, Civilization or something in that genre. I like Endless Legend.
I'm not sure how low-spec it needs to be, but perhaps a coop shooter like Left4Dead, Vermintide, or Deep Rock Galactic.
Fall Guys.
Coop RPGs or ARPGs.