He tried to see if things could work with Brienne and if he could have a life with her but it didn’t work out because he still loved Cersei. And he still loathed himself for wanting his sister instead. So he went back to protect her. I guess the difference is before he was willing to kill to protect his secret but now he’s willing to accept that that’s who he is and he doesn’t care if others know. He’s a flawed person.
I could rock with this if this was actually explored. But once again, this arc is a victim of a shortened season where he fukks and chucks her in the same episode.
If they had devoted time to Jaimie trying to live a new life with a new woman, several episodes of this, and we get to come to a realization that he feels like he doesn't deserve this new life, or whatever other characterization you want to arrive at to justify his decision to leave, then I could at least see what they were going for.
But they didn't do that. People are having to fill in the gaps with stuff not actually developed or shown.
As presented, his entire storyline seems like a gigantic waste of time. We didn't need 8 seasons to tell a story about how Jaimie is obsessed with Cersei and nothing ever will change it. We got the idea by season 5.