Grindelwald conquers America and keeps Graves as a concubine. After Dumbledore defeats Grindelwald, Dumbledore helps Graves work through the PTSD, and eventually the two fall in love and either marry or are just long-term partners. Every now and then, though, Dumbledore needs to go visit Grindelwald, either for information, to make sure the security is tight enough, or out of residual feelings. Whenever Dumbledore stops by, Grindelwald makes a point of asking after his former sex slave, and pointing out how, if Dumbledore had joined Grindelwald, they could have shared Graves.