He was but when Kanye was breaking out, Jay started using his production and it produced his most classic albums. If i recall correctly (if this is not someone let me know), he wanted to keep using Kanye for production on his tracks and did not support/care about Kanye's aspirations to rap (Jay's MO). Damon Dash was the one who fought for Kanye not Jay and Kanye I believe has said in hindsight that if he had to do it all over again he would have stayed with Dame but at the time he was a young kid and Damon's approach was abrasive vs Jay who was a smooth talker.
If you listen to Big Brother, Kanye touches on the negatives of his relationship with Jay and how he feels sometimes that he gives and Jay just takes.
+1 and it is telling.
So you're basically saying there's no love lost between Jay and Kanye, right? So, they were never really friends to begin with.