I wish it wasn't called a rape fantasy, but there is no good way to call it in two words.
I call it power play sex where a woman is surprised with hard and assertive sexual intercourse.
Given I have history with this topic :-) i.e. the sliver lining.
Here is what I would do as a man who had a negative experience with a woman that had this desire. We would talk about it and I would state over the next X days, this would happen. On my farm, if this was the case when she is alone, I would take her by surprise there.
If I was traveling like I would, I would purposely come home a day early and do this. If my partner was a business traveler, I would surprise her in hotel room.
So the key thing is consent, talk and discussion.
On my front, I deeply desire to be taken by female partner. From a therapist discussion, the desire is to feel the act of intimacy with a person that I love and when or if this happens she believed I would be healed 100%.
So you are so right .... there is nothing wrong with fantasies. Talk, consent, love and care (especially after care). As a 5'11" large man .... trust me I can make a woman feel small ... but consent consent consent ..... and once done ... watch out because poor you.
My partner is like you. She has never been assaulted, and I have made sure she has had a safe home and place, and given I am a presence ... she can gain some protection from me. That is something I am very proud of ... her safety.