For following along on the fundamentals you'll be fine. As long as your guitar is in tune, after a few days you won't even notice because you'll be listening to your own guitar more than his. When you get to the point of playing along with the jam station tracks your guitar will sound like it belongs whether electric or acoustic.
Example: I'm sure you and your wife have very different voices, but if you sing a duet together, it can still sound good as long as you're both on key.
If anything, your wife may have more trouble getting her fingers toughened up to play on that guitar. I found that an electric and nylon acoustic allowed me to play for longer periods until my fingertips got calloused enough. Also the original cheap acoustic that I started out with had a very high action and was difficult fretting those chords using the first two frets. So if that's the only thing that keeps her from wanting to move on, you might consider a nylon acoustic. Again, you'll be saying, "this sounds so different." But after a couple days it won't sound funky to you any more.
Thank you, thank you, I'll be here all week.