It's such a personal experience that any advice will be just a shot in the dark but I'll try.

If you want to fix it, I guess you might have to wait it out. Just find the time he's comfortable and not occupied with music and only then try to explain your, I beg your pardon, inattentiveness to his music.

Even if you don't fully discern the details of his music, ask him to tell you about it, ask about the instruments, melodies, specific lyrics, the song structure, inspiration, the creative process, all those details non-musicians often don't care too much, but for a musician are of utmost importance. You will see the fire in his eyes when he starts telling you about it.

General words of praise, like "It's a beautiful song" are OK, but we all have heard they so many times, they make not much impression. Musicians love to be asked about their creations, so do find some time to talk to him.

Also, I wouldn't blame you for what happened. Discussing art is not a simple thing if you're not into it. And in your case it could well have been an inadvertent "failure to communicate."

Edit: spelling