The rapist may not yet have chosen a victim. Again, victims are chosen based on perceived vulnerability. Nearly all gang rapes have been planned in advance. All rapists want is sex. Rape is about power, control and anger.
Many rapists have wives or girlfriends with which they have sex.
Rapists want to dominate and humiliate - this is not sex, this is violence. If you are dating someone then it's not rape. Forced sex is rape, whether it is your first or your fiftieth date. If the victim is under the influence of drugs or alcohol she or her cannot give consent. If consent has not been given, then it is rape.