When she says no, that should be the end of it. If things are getting intimate, the woman has every right to end things whenever she wants to. There is no unwritten rule that says once a woman does this or this than she must have sex. There is no threshold where sex becomes a must. It all comes down to decency, and how we need to treat others and respect them.
Nobody is property.
I could not imagine myself getting to the point where I could no longer control myself and would be forceful. There is no excuse for that behavior.