I think you will find the CPS won't bother with more than you think, especially rape case's, my niece was raped 2 years ago by her mates husband, the cps didn't want to know, the police told her it wasn't uncommon, those cases are so hard to prove, they often won't bother unless the evidence is really good.
Its a bloody grey area, and like any law can be manipulated, often to the benefit of the accused.
There are some bad C**TS in this world, who will take advantage if they can.
I know of some lives really messed up by fuckers with no conscience or respect of other human beings.