So I finished mission 31. And now I'm just repeating the same missions in higher difficulty, which is just frustrating. Did the game end after chapter 1? I don't want to leave this game unfinished after the many hours I put into it. But I really really want to move on. Is the game done after chapter 1? 

Sometimes this game can be brilliant, and other times it can be frustrating as hell.

Mission 46 is the "last" mission in the story. You have to endure these repeated missions in higher difficulties because after Chapter 1 the game takes a huge hit in quality and starts padding the fuck out of everything.

So no, you're not done yet, but don't expect much from now on, really.

Is there a way to not do the repeat missions? Holy fuck is this annoying. 

Nope. You gotta do that in order to unlock more story missions. xD

Fuck that shit. I deleted it already. And I'm considering my self that I completed this. 

Metal gear solid 5 did provide with some of the most frustrating apsects if gaming for me this gen. Despite being a fantastic game at times, it, for some reason, insists on being a pain in my ass at others. 

It's probably better this way because the final story mission is literally replaying the prologue of the game in the hospital.

You have to play the prologue again its something called "The Truth" its actually not just a repeated mission. Its different and it ends the story. gotta do it man, its really good

btw wth you finished chapter 1? there is chapter 2... you are nowhere!

After Mission 31 there are still many missions left that are NOT repeated missions, so forget everything everyone told you there is still a lot of story left. Instal the game and keep on playing you have litterally not seen anything yet!!

There's so much misinformation in this thread. You don't have to play a single repeated mission. I'm not sure of the exact progressing conditions, but they most certainly do not involve playing a single repeated mission. Presenting them in the mission list as story missions is very misleading, but you don't have to play any of them. So yeah, you uninstalled the game for no reason.

After Sahelantropus, and thus the end of Chapter 1, there are missions up to Mission 50.

Out of those 19 missions in Chapter 2, 12 are repeated missions. Then you have Cursed Legacy, which is just about extracting two containers through fulton, Extraordinary which I think is picking up the film canister, and Proxy Wars, which is about to destroy tanks (something you already do in a similar mission from Chapter 1).

It basically means 15 missions play either as a replay of a previous mission in a higher difficulty, or basically demand the player to do very simple mundane tasks.

It's true that he's missing a chunk of story by not doing Chapter 2 - one of those four remaining missions, Shining Lights, is pretty great and pretty much enjoyable in many ways. The one of Quiet is also important, but since the OP is getting bored of the repetitive missions, and he has to endure basically 15 of those, I don't think he'll be able to push himself through them.