They never actually act like friends. Instead Anakin goes on about saving Obi-Wan and Obi-Wan denies it. They have the absolute worst on-screen chemistry of all time. ANH at least makes it seem like Vader and Obi-Wan really were good friends but the PT fails at actually showing it. It doesn’t help that the lightsaber fight is so long that it gets boring and many of the camera angles are too close to even see what’s going on in the over-choreographed battle. The climax of ROTS fails in many respects, there’s no point in even arguing that it’s good. I suggest looking up “Plinkett” on google Scott.