I appreciate that; the feeling is mutual.
In situations like this, one can either believe the victim is telling the truth, or they can believe the victim is lying. Obviously, if there was evidence in either direction, that would make it much easier to decide who to believe, but since we have no such evidence, all we have to fall back on to make the decision is principles. In principle, I believe that less harm is done overall by believing the victim.
If you don’t believe the victim, you are branding them a liar. There is no neutral path here. You can say you abstain from forming an opinion, but that only supports the status quo, so consequently it is the same as disbelieving the victim. There is no neutral path here. Since it is an interpersonal matter, I believe less harm is done by believing the victim than by disbelieving them. If we were litigating the matter to determine guilt and assign consequence, that would be a different story. In that case, less harm would be done by presuming innocence.