The explosive stage. Endorphins are raging throughout the system now. For the abuser, it could actually be a sort of high, sometimes blocking out memory. Then the honeymoon stage. It is not uncommon for there to be sex directly after the explosive stage.
Adrenaline can cause the man to have an erection.
Even prisoners walking to their final destination at their execution will have an erection. The problem is that as I mentioned earlier, adrenaline is short acting. The erection will quickly leave, orgasms are difficult without the vasopressin. Many men who are rapists and abusers have trouble with orgasms. In addition, the adrenaline is like a drug requiring them to need more and more in order to gain any sexual satisfaction.