Platformer recomendations for my wife

Playboy the mansion

Rayman Legends!!

I have a sister who has never played video games and has failed terribly every time she tried! But Rayman Legends is so simple that she was actually good at it and we sometimes used to compete!! I tried playing other platforms with her but she either got bored of them or couldn't understand.

I like Shantae & The Pirate's Curse
and Songs for a Hero it's in portuguese though (for now), but I only speak English and it's still awesome
both of these remind me of monster land games, particularly the latter

Oddworld: Abe's Oddysee and Oddworld: Abe's Exoddus. They're very old platformers but still among the best puzzle platformers ever made. Graphically I'd say they still hold up well today, the art style is really something. The game's world is also interesting and the atmosphere is great.

The Purring Quest for sure. I just bought it some days ago, and it's just awesome, very cute, very good music, and not too hard.

What about Fez?

Have her start with Max and the Magic Marker and then move on to Max: The Curse of Brotherhood (so good!!)

Didnt see anyone mention freedom planet which is aboujt as good as platformers come for steam imho
Also Jumpjet Rex is a great platformer but may be too difficult

Super Meat Boy just kidding :D
Maybe A Story About My Uncle?
Also the newer Rayman games (Origins and Legends) are good too, and this will be a bit weird, but I recommend getting Speedrunners.
Speedrunners is a competitive game, where everything happens fast, but this way your wife could improve her reaction time, and accuracy while playing platformers.

Some of my personal favorites:
Castlevania: Mirror of Fate
Bloody Trapland (pretty tough game!)
Battleblock Theatre
Contrast
Scribblenauts Unmasked

More:
Nihilumbra - Beautiful, compelling story, which takes ~ 2 hours to complete. Devilishly hard puzzles afterwards. but not during the main story.
Contrast - Gorgous, interesting gameplay, and not terribly hard; it has a good story to boot ;) My only complaint is that it's too short!
Stick it to the Man! - I found this to be absolutely delightful (despite the weird art,) and though there are some sequences that could be hard for a beginner, those areas are more puzzling out the sequence than anything else.
The Swapper Oh my gosh, amazing game. Deeply environmental, compelling story... It has a great puzzle-adventure dynamic that happens to include some platforming. My review is HERE if interested :)

Castle of Illusion

Not sure about difficulty, but a lot of people seem to like Moonlight. It's very short.

Thanks for all the ideas, guys. I appreciate it.

Out there somewhere. It's tricky in a few places, but it's not really hard as in getting killed often

I just finshed 'Hell Yeah' one of the best games i played in the last 10 years or so. The achievements are also easy and the game is really funny. Trust me on this one

Freedom Planet
Superfrog HD
The Purring Quest

Trine series and BattleBlock Theater come straight to mind for me. Those games are known for their co-op but I've played through all of them solo and they were a blast.