The myth of Persephone stands out as a point where a god has the opportunity and even the motive to rape a woman, but chooses not to. Yes, he—technically—kidnaps Core, but this is mostly due to Zeus waffling over an answer. Hades did the right thing in going to Zeus and asking for permission to marry Core. This is unheard of in mythology.
Zeus in particular never asked for permission for, well, anything. He raped his mother, Rhea (which makes the fact that he went to her for help particularly interesting). He raped Hera, shaming her into marrying him. There’s little to go on regarding Core’s inception, but given the pattern of behavior (which is continued on with many mortal lovers), it’s likely that Zeus did not act the gentleman with Demeter.
Hades, however, asked permission, but not hearing a “no” acted on his own initiative. His behavior after bringing Core to his house was exemplary. Core chose not to eat, but she was provided for. There is no mention of Hades forcing himself on her. She was not harmed her in any way.
Hades’s intentions are pure in this entire endeavor. Unlike Zeus, who wants to exercise his power over others and sire children, Hades only wishes to have a relationship. In the underworld, he is far removed from business of Olympus and the mortal plane. He is, in a word, lonely, but still chooses to bide by civilized behavior.
He wishes not for the purely physical from Core, but for her to be his wife. In a mythology full of affairs, rapes, abuse, and violence, Hades’s actions are uncharacteristically civil. No other Greek god behaves in such a civilized manner.
But did he take Core against her will? Stay tuned.