The criminal conviction and its consequences will still exist because the the State and or government prosecution has a duty to protect the public against a convicted sex offender, regardless of the relationship between the parties. Thus, because this person was convicted, the State has a duty to have this person report themselves as a registered sex offender. You may however seek to have the criminal record expunged and the sex offender registry expunged, but keep in mind that most states do not allow sexual assault crimes to be expunged from a persons criminal record.