Colorblind is already a metaphor on itself in this case. It's about failing to open up. A lot of people see things in a certain way and then something might happen that makes them come out of the shell and see it all in different colors and shapes. But it takes time to get them out of the "colorblind" variation they have stayed in. I think it's talking about falling in love again. A lot of songs from Counting Crows talk about that, actually. So it's not exactly a surprise. Besides, this was one of the main themes for Cruel Intentions and the whole idea was in there haha
