to be in a relationship with or marry a person who is unkind or unfaithful (originally used of a woman)

她感叹自己遇人不淑，在这段婚姻中受尽了委屈。

to associate with, trust, or work for a person of poor character

他在创业初期因为遇人不淑，被合伙人骗走了所有资金。