Or are the male victims of violent women too afraid to report it?

They literally can't in a lot of areas. Legally, the Duluth Model is the most commonly accepted form of domestic violence enforcement and within it the man cannot be the aggressor short of a set of super specific scenarios no one will ever meet.

By a man being larger than her, he must be the aggressor by that model and even if they catch her mid stab on him unarmed he is still not by default a victim. Because its a feminist theory that says that domestic violence is a "society level taught patriarchal threat."

That's without getting into them pulling a reversal and starting to cry and acting like you hit them when the cops show up, because they are legally required to arrest someone if they are and you are the easy option.

So if you report it, you will likely end up getting arrested yourself for domestic violence and get branded by it, and you will have to go through a lengthy legal case to reverse that. At that point why would you ever want to risk reporting it? That's not fear, its purely rational caution.