Orphaned baby monkey doesn't want caretaker to leave

This adorable Vervet Monkey was orphaned and rescued at a very early age, and had to grow up and a wildlife center. She will be released back into the wild, some day, but in the meantime, she needs a foster mom, which is what her caretaker is to her. In order to be able to return to the wild, she can't be humanized, which means that she can't be used to people, or she would approach them once she's free, and it would result in her either getting captured and kept as a pet, or killed, so her foster mom can't do anything a monkey wouldn't do, such as talking to her. But since keeping her company is required, the caretaker sits with her for hours, but even after all that time, the baby monkey still doesn't want her to leave, and keeps jumping on her shoulder, and screams and she finally manages to.