And now...further sociological cant

Apparently my brother was disappointed at not getting a response to his response, so to speak, in our little ethics debate, but as should be clear we are not really disagreeing about the central issue. I say that it is natural for humans to make moral distinctions in their relationships with different people; he says that the law should not be used as a surrogate morality to enforce those distinctions; I agree but feel that the individual may have obligations in this regard that go outside or even in opposition to the law. So there you have it. Now for my own question about domestic violence issues: why is "I have to go" always the cue for sex in movies? Does "I have to go" tacitly mean the same thing as "no" under our byzantine rape laws? Is Hollywood therefore endorsing a pretty lethargic form of sexual abuse? Is this ("I have to go") a line that would actually work at parties?