Why is a girl is allowed to file complaint for rape or sexual exploitation after weeks of the incident?

It is common to come across news items in the newspapers or on the TV channels whereby it is reported that a girl was raped or sexually exploited by a relative or a teacher or a master or a stranger for weeks or months and sometimes even for years. How is that possible ? A rape can happen once in a while by a gang of goons, but how can a man alone rape a girl or a woman alone unless the girl or the woman also co-operates ? Is it not simply impossible to penetrate when the woman is resisting hard ? And what stops her to immediately report the matter to the nearest police post or to at least her family members ? Further how can a woman be sexually exploited over the long period of years unless she herself willingly continues the relationship ? Is it not possible that the so-called abused woman entered into the sexual relationship willingly and continued the same for the sake of pleasure or with some hidden motive like getting a role in the films or some monetary gain or getting a job she did not deserve in the first place from the man in question, and later on, when the man refuses to oblige her, she becomes vindictive and slaps the charge of rape or sexual exploitation ? Since the law is heavily loaded in favor of the "victim", many a respectable names have been sullied for no real fault of theirs. The upcoming actor Shiny Ahuja just being only one of those unfortunate victims of a skewed legal system.