Peach blossom luck, you can meet the opposite sex, such as getting married (whether real or imaginary) but it won't bring you bad luck.
Peach blossom robbery, although it also meets the opposite sex, will eventually bring you bad luck, mental or physical harm.
That's how robbery came about.
Robbery is luck, and luck is robbery.
Just look at it from another angle.
Fate calls meeting a woman "peach blossom luck", and you can avoid it.
It is the peach blossom robbery that brings you bad consequences because of the inevitable femininity.