Anakin/ Darth is the epitome of " I hate you/ I love you". He calls Obi wan wise all the time, then proceeds to call him a failure. He says before their fight that he is what Obi wan made him, yet, in the end, tells him it's not his fault. In my opinion, he acts like a very bitter jilted lover. He never calls him wise in his face, only behind his back. And he doesn't tell him it's not his fault until Obi wan starts crying.
When Palpatine told Anakin to leave unconscious Obi wan behind, Anakin told him that he would have the same fate as them. See, Anakin being immature and very passionate, can't tell himself apart from other people in a healthy way. You are either his enemy or his ally. He'll either die with you or kill you. There's no in between. He'll either rule the galaxy with you or choke you if you deny him ( Padme ). And he knows that he is in pain as much when he hurts the people he loves. More than anything he wants to kill himself. But he'll kill you first because he perceives you as something that's his, an "unfinished business". An egocentric type of love.
He reminds me of the " love me or die" song so much. The narrator/ singer knows that he did something evil ( poisoning and killing his love interest after getting rejected ). He knows that she didn't deserve it, yet, being too far gone like Anakin, believes that there wasn't any other way. In the end, he laments that both of them will go to hell and meet again. In his mind, even tho she is perceived to be the lesser evil, they both sinned and for that, they deserve it.
I believe that's how Anakin perceived his own situation too. He loved Obi wan and he knew Obi wan loved him too ( it's possible that in the song, Matilda loved the narrator but being repulsed by his dirty money and connections, turned him down ).
But in his mind, he wronged him, and Anakin wronged Obi wan too. And for that, they both deserve to die and meet in hell.
It's canon that Anakin felt extremely lonely and empty after killing Obi wan. It's also canon that more than everything he was miserable and hated himself. He was aware of his atrocities. I believe that he thought that he would pay in the afterlife. I believe that he thought Obi wan would be there too, paying for his own sins.
Till Luke came and showed him what true love is like. Non egocentric, more beautiful than ugly, patient, idealistic and forgiving. Darth seeing so many qualities in Luke that reminded him of Padme and Obi wan softened at first his heart a little bit, opening the way for Luke to save him due to his own perseverance in the end.
When Anakin died, he met Obi wan again but not in hell and he accepted that, now knowing how to let go.