The CORE incident and Sans death would've had a major impact on Gaster's emotional/mental condition. The failure to break the barrier and delayed realisation to Betty's true nature would have left him questioning his capability to protect others greatly. Even though he did have this ability in S1 to battle against Sans as a source of desperation to escape the void. I guess Gaster just doesn't have that much of perseverance left after these to events. @camilaart













