I like to think that the only people who believe that Ani's and Obi's behavior around each other was genuinely friendly lack empathy. There's an emptiness to it. Like they're pretending (or just acting badly.). They try to fool you into believing they have a friendship by making references to events that never occurred on screen, which should have. Like how in the original trilogy and TFA you actually watch those moments and see them bond. The friendships in those movies are actually believable.

And as for Anakin's massacre of the Tuskens, you can either edit it and any mentions of it happening out entirely and he movie wouldn't even change, or you can understand that Anakin massacred a village of primitive indigenous people and it went completely ignored by the rest of continuity. If Ani and Obi were such friends, you'd think Obi would have basic human empathy for his "brother," and try to help him through such a trauma which Ani wears on his face at all times. Anakin is in hell and the Jedi don't care (though I will concede that's the point).

So, no, beteeen bad acting and bad writing, I don't believe for a second Ani and Obi were friends