Regarding Gríma and Éowyn

[The Only Real Estel]

To me their relationship, actually his relationship with her, is the perfect example of wanting something you can't have

I wouldn't be suprised if not being able to have something he wanted would've been the motivation for him to take it anyway.

Ahhh the only way he would be able to overpower Eowyn would be if she was already dead

He's not very physically strong anyway; she could probably overpower him if necessary

Not necessarily. I don't think that Eowyn would've been able to stop him be means of her physical strength, Grima was stronger than her physically, in my opinion. Still, Eowyn probably could've at least escaped, if only because of her strong will. Whether Grima would ever have even attempted to rape her or not is really almost impossible to answer.

edit: corss-posting down to the minute with symestreem