Most Helpful Guy
I've seen this before, and I loved the analogy; it's so open to interpretation.
The way I see it is that there's a guy, and a girl, obviously. They both begin meeting, perhaps date, and get to know each other. They begin to 'mix' (the whole purple analogy), making a perfect blend, or in real life, a perfect couple --at least that's how the guy sees it. Sadly, the girl doesn't see the perfect blend, "purple wasn't for you".
It hits me every time, and one of my all time favorites.