[someuser2345]

> Of all people to loose faith it would be Luke? Riiiight.

Yes; Luke never really dealt with betrayal. He only ever knew Darth Vader, so he wasn't betrayed by Anakin the way Obi-wan and Yoda were.

> And Han and Leia just have to be divorced? Ok.

Your son switching over to the side of the people who blew up your home planet would put a strain on any marriage.

> And their son just has to be evil. ... Ok. I'm actually with you on this one; Anakin's final transformation to Darth Vader was rushed, but at least the seeds were there from episode 1. As far as I remember, Kylo just turned evil because the Force wanted him to.

[Auracle]

Luke’s entire characterization in the original movies was that he’d do anything for her friends and that he believed in his father.

In the sequels he plans on doing nothing for anyone (especially his friends) and doesn’t believe in his nephew.