I don't know what the answer is.
Here, in Scotland, we have a Not Proven verdict (which to me reads as "we know you did it but the Prosecution hasn't proved their case").
I think that, plus much more use of Sexual Harm Prevention Orders - eg where the Not-Innocent-but-Not-Guilty person has to comply with certain requirements, like notifying the police of any new relationship that may become sexual.
I don't see why they aren't used more often to be honest. I think they're a great thing to have as an option when someone has behaved in such a way, but the case doesn't meet the impossible standards of Beyond Reasonable Doubt.