An E and F close together will sound one way. An E and F in different octaves will sound another way (and less dissonant). Two violins playing together should choose between the two (at the least) and not worry so much about chords at all. Your guitar player only "really" needs to know about the chords if (s)he is playing chords (or chord tone soloing). Maybe that takes some pressure off?

If I was talking to you on the bus, I'd say buy you a ukulele and a songbook with simple uke chords (with diagrams) and start playing. I did, and then moved to guitar. I still don't know the notes in most chords, but I can play them by making the shapes and hear what they sound like in context. A LOT of "theory" can be absorbed just from playing chords and learning their names.

BIAB 2021 Audiophile. Windows 10 64bit. Songwriter, lyricist, composer(?) loving all styles. Some pre-BIAB music from Farfetched Tangmo Band's first CD. https://alonetone.com/tangmo/playlists/close-to-the-ground