This is all my personal opinion so feel free to take or ignore it as you will:
- Stop thinking that your wife isn't smart enough to play.
This could just be me reading into it, but when I read "too tactical for her" or "think more critically" it basically makes it sound like, "she's too stupid to get it." Remember that MOBAs in general, and especially League, have a very steep learning curve. If she is used to FPS games then its completely normal and expected that she'll have to adjust to the different game type. Has she played other MOBAs? DotA, HotS? If not then remember she isn't just learning League's specific strategies and items but learning how to move around on the map, use a different keyboard setup, and so on. It would be the same as someone who only plays MOBAs switching to an FPS and having to get used to WASD movement (or even a joystick if its a console) and not only having to learn CoD's perks and guns but how to strafe, where/when to crouch or how to exploit ledges to camp up in a weird corner somewhere.
Anyway, could be reading too much into it, but just give her a lot of learning room and be encouraging. Focus on easy mechanics first, maybe stick to a few Champs (I don't actually recommend ARAM but I'll get to that later)
- Don't worry about your win/loss or KDA
She's your wife, not your LCS team partner. There isn't anything riding on this except personal pride, and if you're going to be sharing your personal interests and she's willing to learn them with you, then you might have to pack the pride away and just let the losses roll. If my lady played League (or any other game) with me I'd be ecstatic.
- Now, how to actually improve from here:
There are a lot of different routes to take, but I'd recommend just finding what your wife likes the most about League or similar games, and how she learns best. Does she like watching Let's Play videos, or streamers for CoD or her other games? Then maybe just have her watch some streams. Does she like really competitive games? Watch LCS matches and talk about why they're doing certain things or point out their strategies. Does she like the nuts & bolts, the behind-the-scenes mechanics behind why certain abilities work a certain way, or understanding the difference between Spell Effects and On-Hit Effects? Read through the Wiki, it has a ton of information, and Knowledge Is Power. Or maybe she just likes jumping in head first and learning through trial and error. Then ignore your loss streak and start queuing. Maybe try a team builder game so you can focus on a specific role, maybe you two can duo bot together, you support her playing an ADC? Or vice versa. Or switch each game.
- ARAM, a double edged sword
On the one hand ARAM is quick and easy to jump into. However its often messier than SR and strategies differ. With no regular laning phase you lose a lot of mechanical skill around last hitting, warding, objective control, and expecting/calling/setting up ganks. Not to mention managing her mana, knowing when to recall, etc.
I'd recommend sticking to SR, but agree to only play a few basic Champions only she really understands them. IMHO its more valuable to master one Champion than pick up and try out a dozen of them. Have her learn one Champ she really likes. Play with Smart Cast, have her learn their ability ranges, what their different build paths are, get used to their CDs, etc. Have her start there and show her a good build and why its a good build (why do you build IE on Ashe, but not on Vayne? Why does Kalista build Runaan's when almost no one else does? These are second nature to veteran players, but can be misleading for new players. "Oh, well they built X so I should build X")
's cage, that's what it does. Keep an eye out for when he puts it down.
Never needs to be patient and can carry hard no matter how far behind. Can wreck top mid and sup. Learning Annie is pretty easy and then she will have a powerful champion to use to learn the rest of the game with.