This trophy is the hardest trophy in game. To get the trophy easier, use this method:
1.
Complete the game on Easy. Try to collect as many supplements and parts as possible for upgrading Joel and his weapons. Don't use supplements to upgrade Listen mode. Because it will be disabled on Grounded mode. Also, fully upgrade Shiv master (this is not required for "Everything we've been through" trophy, but this is effective while open conflict with infected).
2.
Start New Game+ on Easy. You will not have other option while starting new game+. Because You have finished the game on Easy.
3. As soon as game begins and you take control Joel's daughter,
save game and exit to main menu.4.
At main menu, choose Chapter Select and select the 1st chapter "Hometown".5. Notice! You can now select Grounded difficulty.
Select Grounded difficulty and begin to play.6. As soon as game begins and you take control Joel's daughter,
save game and after saving process ends, check save file in "save game" option. In description it
must write "New Game Plus".
7.
Beat the game.
8. All difficulty and difficulty+ related trophies will unlock.
Good Luck.Notes:
1. You can easily skip most of battles. I have used this helpful video -
Also, I didn't follow everything the gamer does in this video.
2. After completing 5th chapter AND at the very beginning of 6th chapter
save and exit to the Main menu. Check the chapter "Bill's town" via "Chapter Select". Because its 1st subchapter will show that You didn't complete it.
This is bad Glitch. Replay this subchapter and play until you exit from church and reach to the graveyard. Save game, exit to the main menu and on "Chapter select" select the 6th chapter - where you left your game. When game begins,
save game and continue playing.P.S. Give your question about this awesome game anytime, if you have.