In a lot of ways rape is subjective. One party can truly believe they have been raped, the other equally believe they have had consensual sex.
Being found not guilty in court does not automatically mean the accuser was lying, only that the jury did not believe beyond reasonable doubt.
The scenario could arise where the jury found the accuser not guilty of perjury because the same standards have to be applied. That would be even more traumatic for the person found not guilty of rape, casting doubt on his innocence in the minds of many people.
If the person who reported rape retracted the statement before trial she could still be found not guilty of perjury. She could claim she retracted and said she was lying because she could not face the trauma of trial, she was frightened, pressured by her family, believed the police were treating her badly - any number of reasons.
Only the people who were there when it happened know the truth and even then everyone could believe their version of events.
Rape is a heinous crime that should be severely punished. Falsely claiming rape is equally heinous and should be treated equally as severely.
Proving both offences is not so clear cut.
I can well understand why so many men and women who report rape to the police retract their statements. I can think of fewer things more traumatic than giving evidence in court months or years after the trauma of being raped. It must be very tempting to 'just make it all stop'.
Equally it must be a living hell to be falsely accused of rape especially if everything else in the statement is true. It can be proved he was there, sex happened.