Putin asked for NATO membership but was denied it early as Russian president. I guess we made it clear to him that we did not see Russia as a friend.

Imagine telling a kid he can't be in your friendgroup and afterwards you ask him: Why can't you just get along with everyone? Why can't you just be friends with other kids, just like us?

Personally I don't think Russia should have been part of NATO, but perhaps NATO should no longer have existed after the end of the cold war. By keeping it, we basically hinted to Russia: "We still see you as the enemy."