For some reason as soon as I get to the “end” of the game, I completely lose motivation to play. This happened with DOOM: Eternal, Sekiro, Bloodborne, Paper Mario TTYD, Cassette Beasts, Shovel Knight, Oblivion, Baldur’s Gate, God of War, Mass Effect… Pretty much every game I’ve ever played. It’s like the fun part was the journey, and I’ve seen everything the game has to offer, and I just don’t really enjoy the ending process. Feels like a formality at that point.
Not necessarily at the boss, but I have noticed a pattern that I do tend to lose steam once I realize I’m in the endgame phase of the game
Has happened to me with Persona 3, 4 and 5. It’s not that i get bored, but burned out. In the moment I don’t realise I’m near the end so that when I eventually get back to the game almost a year later, I realise I was literally only like 2 or 3 sessions away from finishing it.