What happens if we take gender and sex out of the equation?
Say a Person A, Alex, attempts to intentionally provoke Person B, Bryce, to violence. Alex taunts Bryce repeatedly with insults to intelligence, heritage, appearance, etc and invades Bryce's space as well, getting nose to nose but not actually touching. Alex continues this until Bryce snaps and throws a punch. Does Alex bear no responsibility in the assault? Even if, legally, Bryce is the only one who can be charged with any crime, why should we overlook that Alex was an instigator just because Alex is also a victim? Personally I think it's absurd to take the attitude that victims are automatically blameless because their attackers are without excuse. It doesn't matter if Bryce threw one punch or dozens, Alex was wrong to try and provoke an attack if s/he didn't want to get hit. Bryce is guilty of assault, period, but Alex is still a jerk.
Fault isn't a matter of percentages. If two people cut holes in the hull of a ship, and each hole is big enough to sink the craft, there's no splitting the blame for the ship going down, even if one hole was bigger than the other. Not that this is analogous to a rape case, but my point is that a rapist can be 100% responsible for his/her actions, even if the victim is responsible for whatever they did wrong.