If the genders had been reversed, the artist would have been accused of child pornography.
It does seem like child grooming, doesn't it?
But lorewise, Eternities are special nannies that take care of their one master's for their entire life. They raise, care for, live with, and then die and be buried with their master inside their special two-person coffin.
Knowing that, we can assume the parents of the child died. Maybe Eternity failed to protect them since she is so devastated, so Eternity raised the child alone into a fine young man who took her into marriage.