Yes, that would be rape.
Consider this scenario:
You want to borrow my car. I say no. When I'm not looking, you take it anyway. Initially I'm mad about it and try to stop you, but afterwards I change my mind. "Fine, just take it."
Technically, you committed car theft. However, considering I felt differently about it afterwards, I'm not going to report it. In this case, there is a philosophical argument to be had over whether or not you should be punished as the crime was forgiven by the victim. Regardless, you did steal my car!