Well, I keep thinking the light bulbs will come to me. Why do I not understand them? I feel like I'm asking for a Homer moment here, but I gotta ask. Because I get the colours, and I feel the tenor of the relationship, though I don't entirely grasp it's full scope, that's fine by me. I like "undiscovered" very much, good characterization for the narrator. The blue phrase worked for me, whether cliche or not (I did not read it as such, but that could be a geographical thing).
It's just the damn light bulbs. More than one of them. Many of them? Hmmmm...
The last line is very good. Plum does bring a fourth color in, fwiw. The half-rhymes work quite nicely, almost as though each set of three combines in a way that goes together, even if it's not a perfect match, which would get boring/predictable in this form. I wonder about the full stop at the end of almost every line however. Not a big deal, but I was just learning about counterpoint and the need for variation in syntax, so it was on my mind and I thought I'd share.