If God is one and three persons, one in essence and undivided, but person comes before nature or essence (else there be determinism and necessity), then unity must be an act of the will, non-deliberatively though it ever-movingly rests in perfect, loving, divine oneness.
This always brings us back to the garden where Christ struggled in prayer. Was this the Son contending with the Father, or his human nature contending with his divine, or God acclimating himself to suffering and separation, the result of man’s willfulness? Then “not my will but thine” seems an acquiescence to humanity’s will to kill him. But he said it to the Father. Struggling to obey, to bring himself to the Father’s will was new for him. It seems like human nature became heavy. God struggling is a weird concept. As is God dying. Or having a mother.