Since clamp seems to have an eye thing and a swapping blood theme...for those of you who've read more Clamp than I do; do they seem to have a general way things go after that? MAybe if they do, that can give us a hint as to what may happen.
Well...In TB, Subaru finally realized he was in love with Seishirou after he lost his eye... in X, Subaru losing an eye to Fuuma
really bothered Seishirou, and just upped the angst in general. In RG Veda Ashura cuts Yasha's right eye and (presumebly) blinds him. And both of those couple are "together forever"- Ashura and Yasha because they want to, and Subaru/Seishirou because they're the most obsessive bastards in creation.
Also: eyes in general seem to signify power/status in CLAMPverse: Kujaku and Taishakuten both had a third eye (I think it's called 'Jagen'- not sure) that signifies damnation (deliberate or inherited)- and both got it because of damned love. Also, both were very powerful.
...let's hope KuroFai end up like Ashura and Yasha and not like the others, shall we?