when it comes to obi-wan and luke's 'relationship' , I'm one to disagree with most of the fandom because, honestly, I think Obi-Wan doesn't even see Luke much as a person, at all. Ok, sounds harsh, but listen. I don't think Obi-Wan humanizes Luke, Leia or Padmé, because that's a way for him to remain separated and distance himself from the Feelings.
Feelings he doesn't want to have, he compartimentalizes and represses too much to care on a personal level.
He had a level of codependency with Anakin that ended in a burst of flames (literally) and as result, now he's stuck there having to separate Anakin and Vader in his mind in order to get some peace of mind.
But at the same time, he doesn't bring himself to care beyond a surface level about Padme, or Luke, or Leia. They're just poor victims, they're just some poor lifeforms wronged by the monster that killed Anakin. Padme is just some silly gal blinded by womanly frelings. The twins are just tools to end Vader. Luke is Plan A and Leia is Plan B, and that's as far as he goes.
He had two meaningful relationships through his entire life (three, if you count Satine). Qui-Gon Jinn and Anakin. And Obi-Wan compared the both of them just as much, and both of these relationships turned meaningful in the context of being a Jedi and serving the force. Obi-Wan can't quite escape state of mind that everything he does must, in some way, serve the order and the force.
Luke is just his ex-padawan and brother's child, from some affair he doesn't care about. I'm not one to believe Obi-Wan saw Padme as a friend, at all. Just a means, just some silly thing that keeps Anakin happy (and he would rather Anakin find happiness somewhere else).
Now Luke....Luke's relationship with Obi-Wan is based solely on his desire to know his father. He believes him dead, so the next big thing might as well be the person to claim was his friend. He wants to honour his father and wants to be like him, Luke only wants to be a Jedi because he's told his father was a Jedi
He's distressed when he loses Obi-Wan because he lost the only connection he had to his father (or so, that's what Luke believes), and also because boy just lost his home and family, Obi-Wan was the only familiarity he had keft. Luke's lightsaber is a copy of Obi-Wan's because it's pretty much made out of bit and pieces of Obi-Wan's spare lightsaber. There's no much Luke really does that is for Obi-Wan's sake, it always comes back to Anakin.
So, in summary, Obi-Wan and Luke's relationship is, quite literally, just based on Anakin and it never evolves beyond Anakin. Is like two satellites accidentally crossing paths as they orbite the same planet. And after some mild disturbance, they just continue their orbit
They might cross paths again, but is brief and surface level.