Halo 5: do we know what's happening in the story?

So in the trailers, opening of Halo 2 remastered and other info coming out it seems like Spartan Locke from Nightfall is hunting Master Chief in Halo 5. All this seems to me to be operating on the assumption that we know why. I don’t know about y’all, but I don’t why. I don’t want spoilers for the game but I’m curious, do you all know why this is the narrative arc of this game? What made these two spartans not like each other?

Nevermind, after reading the article linked below it seems we’re not supposed to know exactly what happened. It says, “However, near the beginning of the game, something happens to the Chief and the entirety of Blue Team decides to go AWOL. 343 won’t reveal details about this event, but it’s significant enough that the United Nations Space Command forms a second team of Spartans - led by Jameson Locke - to hunt down Blue Team.”

Theres a story in Halo outside shot da aliens and ruin da game by making it a generic fps?
Oh Halo 1, rip.