I don't think I can get mine to do anything like that. She has been performing as a singer all her life, and we both do some gigs and busking together, but in the past she has just sang along and I've sang and played the uke. But she learned a few chords and started playing, and as new chords show up, she just learns them and plays along now. If a song has chords that she doesn't know, or something is too much for her to keep up with, she just mutes the strings and keeps on strumming. She keeps learning new chords and it works for her. But she insists that she isn't learning to play the ukulele, that she is just playing around with it. Whatever.
I hear you. Your wife definitely has an advantage in that she has a musical background. My wife has no musical background, though she did try to take up piano when our youngest was learning. She's an accounting manager. She's a numbers and statistics person. She's definitely more left brain than right. It's hard for her to hear the beat, or feel the rhythm of the music. She thinks more along the lines of, "What's the strum pattern?" "How many beats in a measure?" But during the group play-along she was starting to hear and feel the rhythm, strumming away. It was neat to see.