solipsist

solipsism: a theory holding that the self can know nothing but its own modifications and that the self is the only existent thing; also : extreme egocentrism

He’d done for her all he could. But choosing to lovingly care for her was like steering a plane into a mountain as gently as possible. The crash is imminent, it’s how you spend your time on the way down that counts.
— Hotel on the Corner of Bitter and Sweet, Jamie Ford (p34)