Obito ultimately preserved their friendship. Even when Kakashi came to kill him, Obito never attacked him. He even watched his girlfriend die at Kakashi’s hands, yet he still did not kill Kakashi that day.I’m 100% sure that even in their final fight, Obito was still strong enough to defend himself against Kakashi’s Raikiri. But he chose not to defend himself—he wanted to die by Kakashi’s hand.