A lawsuit is not the same as a criminal prosecution. One is supposed to remedy damages, the other is supposed to be because it is in the public interest that people follow laws and we don't devolve into anarchy (or more dangerously, some might-makes-right society where it is more beneficial to appease the powerful than it is to pursue what is just).

It is possible for a prosecutor to decide it is not in the public interest to persue a prosecution (or that there isn't sufficient evidence to prove a criminal action beyond reasonable doubt), and certainly the victim's opinion could be considered, but ultimately whether criminal charges should be pursued is and ought to be based on a different test to civil matters, one focused on the public interest rather than mere restoration.