Fall in Love with a Fox

Yuan Zhong is a fox high priest. He is an immortal who possesses the divine hand. With it, he defeated the ghost clan and brought an era of prosperity. Jin Tan Yin is an artisan goddess who makes magical artifacts. She descended to earth to kill Yuan Zhong and get back the divine hand of the god Tang Hua. Yuan Zhong is harassed by his own fox clan and Jin Tan Yin decides to help and protect him. The two of them will have to face personal enemies, and a secret will be discovered. Yuan Zhong rescues Jin Tan Yin from a trap. Reunited again, the pair of lovers join forces to defeat their enemies and restore order in the world.

Source: (Baidu /TvMao)

Both FLs lose their memories and start entirely new lives, while the MLs who loved them re-enter their lives and help them.

Both female leads were top assassins but got injured and lost their memories. Both main leads are investigating the culprits

Both FLs are former/current assassins who work for an escort agency. Both are historical dramas.
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Both are light historical dramas in which the FL works for an escort agency. Both MLs are very devoted to the FL and are at one point poisoned and later cured after almost dying.