I started watching the show after season 2 so i didn't watch Shane and Rick fight. But i think even if i had a bloody fight with my best friend, i would hesitate to kill him.

For the governor, Rick would die if wasn't for Michonne, and in the next episode he was very injured from the fight, that there is a moment that Carl though he died and turned into a walker.

Joe was very cocky and wanted to kill Rick for last after his group had their way with Carl and Michonne, he didn't expected Rick to fight back and bite his throat. Even his group became surprised

If wasn't for Carol, Rick and co would have became human steak.

And Negan had several communities giving supplies for the Saviors, and he thought if he make Rick broken and powerless, he would do the same. And it worked half a season, until Rick decided to fight back.

Kirkman said that Rick would die at some time in the comics and show. In my humble opinion, the show and comics is Rick and Carl story. But i still believe Rick will die at some time and pass the torch to Carl.