Friends before dating love
"If you were new in business and an experienced businessman made fun of you, you would not give up trying to make a profit. In a highly competitive society, we may think that all is fair, especially if we can find a way to make dishonest actions appear legitimate.
Yes, I know, the other person is an adult who is free and responsible to walk away if he or she is so unsatisfied, but like it or not, it tends not to work that way. Especially if it's the woman in this position (as seems to be the case more often than not) she will likely feel that if she pushes for something more than friendship, she may lose the interaction and companionship she currently has.
As I've discussed before, a broad (but sound) implication of this passage is that "defrauding" could include inappropriate emotional — as well as physical — intimacy.