We're talking about groups here, not outliers. It's as simple as that. No one is assuming women and girls are incapable of committing gender-based violence against either gender, whether female (Sandra Cantu case) or male (see: all those women teachers convicted of child rape charges against male students).

Misgoynistic bigotry is the driving force of (heterosexual) domestic violence, not the favorite catch-all excuse:"hurt feelings" ("Overwhelming shame after rejection?" Are you serious? Why is that boys are especially "ashamed" when a girl rejects them?) It's like saying: Yes, during Jim Crow many blacks were lynched and terrorized by whites, specifically white men, but not all of it was due to racism. No, some of it was just "genuine" fear or anxiety about crime. It's trying to muddy the waters.

And it's not like batterers hide or sanitize their misogyny either. Just because misogynistic slurs, rape jokes, and general violent anti-female hatred are common in society doesn't make it any less notable, it just shows how deeply ingrained bigotry against women and girls is, which goes to explain why misogynistic violence--in which gender plays the determining factor in selection--is at damn epidemic levels.

Women and girls suffer a range of hurt feelings as well and yet they don't systematically target victims on the basis of their (male) gender. Men and boys do and women and girls are overwhelmingly their victims in such crimes. That's the key here: gender was the determining factor in selecting these victims for torture and slaughter. Incorporating sexuality (rape) or "love" (domestic violence) doesn't cancel out the effect or justify their behavior.

Hell, females don't even commit generic violent crime anywhere near the level that males do. Why? Because we're raised differently than women and girls. And that's without looking at bigoted violence, whether misogynistic, racist, or homophobic, which is almost universally committed by males. Or to take another example: Why is it that white police officers are way more likely to kill undercover black or Latino officers than vice-versa (assuming there have even been any cases)? Racism. You can claim that these white officers were just scared or that even black officers kill undercover officers of color, but that doesn't get at the root, "Why?" Specifically, why were they scared enough to shoot, when in a similar situation with a white person they weren't?

With regards to homosexual domestic violence: yes, neither gays or lesbians are immune from misogyny (or homophobia for that matter) either. What I do know about batterers, regardless of orientation, is that when they kill, they kill to keep. It's a final act of control and contempt, not mere jealousy or frustration. It's usually why they end up killing themselves afterwards: they lost their scapegoat, their coping mechanism.