It’s really hard to suggest games without knowing what you guys normally would play. You mention puzzle games. There are a ton of two player puzzle games that you play head to head which might be fun, but it isn’t coop exactly. I highly recommend super puzzle fighter ii turbo. It’s available thru emulation and I think maybe on steam via that capcom arcade thing. There are lots of games that fit into that category if it ends up appealing.

If you have access to any of the games mentioned… maybe just have her try some of them and see what clicks. I know with my wife she wasn’t really a “gamer” at first… and I just let her loose on my steam games and a few that she would have never considered before became favorites like half-life, portal, l4d2. Most of the valve stuff holds up really well and makes for good primers into FPS style gaming. We also got really into coop minecraft and dungeon defenders so hundreds of coop hours have been dumped into those. I’d pick a bunch of genre styles (fps, puzzle, survival, etc) and just show her some gameplay videos if she’s reticent to play them sight unseen… see if anything sparks her interest. Then pick out some of the more well regarded titles from them to dive into. There are definitely classics that are considered classics for a reason.

As for roboquest… I’ve enjoyed that one. The dev kept putting out content patches so it’s gotten a bunch of content dumped into it. Fun solo and coop. I personally love the pop art comic style. The progression is rogueLITE… so you’re slowly building up new stuff in your hub as you play, which makes for a nicer experience, IMHO. They even have a free demo on steam if you wanna try it out while you wait for a sale.