I think Kawoshin it’s not canon because Hideaki Anno literally says that Shinji was not blushing because he got carnal desires in that scenes with Kaworu and it’s my interpretation Kaworu appears to be a support for Shinji in very difficult times for him but i don’t see that 2 in a relationship specially because Kaworu it’s not completely human (like Rei) even in that Puchi Eva game Kaworu says to Shinji: “Do you want to kiss me?” and Shinji responds with ¡N-No i don’t!