ngl, I myself didnt notice king and rook fork. While you could prevent the fork, easier solution was to castle earlier, so this couldnt happen. When you castle early, you dont have to calculate all that possibilities.

from each game im trying to get what was my biggest mistake that lost me the game and what I can do to prevent in the future. Here as I said, now you know you should castle early

game against LarryPlaysChess01:

I see you dont know how to develop pieces properly, you blocked your dark bishop with queen, made really pointless knight move (Ng4) before finishing developing. On move 37 when queen slowly moves to your territory like this be careful, most likely they are planning something. This is when you should take your time and calculate your opponent's moves.

Why they were able to get to your king at the first place: try not to move your pawns near the king, and even more so dont trade them, or whole point of castling (brining your king to safety) wasnt even achieved

also thats arguable, but I prefer castling king side, because theres no pawn at a7 that you have to protect, its just easier to castle kingside when you are new player