>>3561214>>3561208He said he wanted to make Shinji happy but, in reality, he was trying to be happy vicariously through Shinji because he felt they were alike. He was a sad lonely looper who was doomed to loop and live for all eternity, but Shinji was relatively "free", so he figured that he would become happy if someone who was "just like him" became happy. Kaworu's main motivation was finding his own happiness, it's just that he accepted that fact only after Kaji helped him realize the truth.
That being said, it's not that he didn't care about Shinji. He still listened to what he had to say, tried to cheer him up, and encouraged him to change. He genuinely enjoyed spending time with Shinji like in the stargarzing scene where he admits that he didn't know laying down to watch the starts could feel so good and thanked Shinji for inviting him. He also accepted with a smile that Shinji had changed in 3.0+1.0 and allowed him to get rid of every Eva and be happy in his Eva-less world. So, he cared about Shinji, but the "I want to make you happy" part was just Kaworu deluding himself into thinking that he would be happy if Shinji, someone who mirrors him, was happy. Another problem was that Kaworu didn't know what Shinji's actual happiness was until their goodbye scene, so yeah...
