Why was Luke Danes out of character for the sixth season of Gilmore Girls?

Why was Luke Danes written out of character for Gilmore Girls' sixth season? It was as if, the writers had ran out of ideas for Lorelai Gilmore and Luke's relationship and wanted to figure out a way to get Lorelai with her former high school boyfriend (and her daughter Rory's father) Christopher Hayden. In order to do that, the writers had to create forced drama between Luke and Lorelai along with Luke being written out of character.

Luke's change started in the sixth season episode "The Prodigal Daughter Returns" where the writers had Luke make a big deal of telling Lorelai they needed to be honest with each other. However, to then later turn around and have Luke not tell Lorelai when he found out he was the father of 12 years old April Nardini. April had stopped by Luke's diner to see if she could use a hair sample from him for a science project. Luke didn't know that the project was to determine whether or not he was her father. He was certainly surprised when he saw her project.

(Gilmore Girls season 6 episode 9 "The Prodigal Daughter Returns")

It's understandable that Luke would be surprised after finding out he had a daughter. However, his actions afterwards in regards to Lorelai made absolutely no sense. Instead of being honest and letting Lorelai (who was his fiancée) know about April, he hid it until he had no choice but to tell her. But Lorelai finding out didn't improve the situation because then he didn't want her to meet April. He was insensitive to Lorelai's feelings and excuse given was that he wanted more time to get to know his daughter before she met Lorelai. He felt that with Lorelai's exuberant personality, he would be overshadowed and easily forgotten. Again, this made no sense.

All the things Luke was doing started to push Lorelai away and have her rethink their relationship. They eventually broke up at the end of the season which lead to Lorelai and Christopher getting together in the seventh and finale season. Despite, dating and getting married things between Lorelai and Christopher didn't last and it left an opportunity for Luke and Lorelai to rekindle their romance. I still don't understand why the writers created unnecessary drama for Lorelai and Luke while at the same time writing Luke out of character. What was the point of doing any of that? Was it to see if a relationship between Lorelai and Christopher would have actually worked? That could have easily been answered without having to maneuver Luke out of the way but that's the decision the show went with.

Prior to the sixth season, Luke was always shown as being a kind and caring, honest and upfront person who didn't lie or mince words. Which is why he would have told Lorelai about April immediately and he wouldn't have pushed her away in order to get to know his daughter better. Luke's love for Lorelai was obvious from the first episode and it's hard to see why the writers decided to have him ignore her and her feelings but I guess it made for excellent drama but did it need to be at the expense of a good character.

Luke Danes is a fan favorite character because of his kind heart and gruff exterior and the wonderful steadfast way he was written. However, the writers did a disservice to his character in the sixth season by turning him into an insensitive liar as a way to get Lorelai with Christopher. Only to reverse course in the seventh and final season, Luke was back to being written how he was before along with the start of a rekindled romance between him and Lorelai near the end of the series. A character should never be written out of character for forced drama, it just signals that the writers have run out of ideas.