I don’t think there is any way to deal with this as a society unless those who feel they are victimized report it immediately, get it on record, and evidence is gathered as soon as possible from the event. It’s disturbing to know that people don’t report crimes when they are witnesses or perhaps even victims. It might be hard for them to do that, and in all instances there should be some resource available to alleged victims so that they can get whatever emotional or other help they need.
Even that may not conclusively determine if consent was given in a single case. I’ve read a lot of print and text about rape kits. For the Rose accuser, a rape kit could only confirm that the sexual encounter took place, not whether it was assault. It wouldn’t be useless, but by itself it would not be enough to determine any culpability.
However, if there is a pattern of people being victimized by a single individual and evidence is gathered in multiple instances, then there’s a lot stronger case to be made about whether the person accused of assault is engaging in a pattern. First time may not be a strong enough case, but each subsequent report would clearly there’s a problem. This is something that could have clearly applied with Bill Cosby, but very few of the women made criminal complaints. It’s that lack of evidence for the earlier alleged assaults that allowed Cosby to continue acting the way he did for decades.
Domestic abusers never just stop, they keep hurting their partner until the partner is dead, leaves, or there’s some other larger consequence to the sense of power and entitlement. One study I found stated that a repeat offender for rape will attack 5 or 6 people before being stopped. Someone who can get away with awful behavior isn’t going to just stop on their own unless they realize there are consequences for that behavior. And the only way there can be consequences is if victims know they are victims and report it.