Feature film "Men in Black II" is continuation of the History of the two secret agents with Naughty alien creatures. After the last case of teammates their lives little changed.
So Jay erased the memory of Keya and he turned into a normal, average person working at the post office, living a boring, measured life. But Jay all these years continued to work for the benefit of mankind and struggled with extraterrestrial debris.
So would have continued on, but with the arrival on Earth of the evil of interplanetary criminal who chose the guise of sexual beauty, Jay needed reinforcements in the form of his former team-mate. However, the memory is erased, Keya he remembers nothing of her past life and then Jay have persuaded a colleague as well as recall skills.