I have not entirely ruled out the possibility that Ford is making a false allegation, but I still find it far more unlikely to be the case.
There are a relatively small number of people who might conceivably have been in a situation to make such an allegation without it being somewhat easily falsifiable.
That someone would be within that group, and have documented their assault with a therapist years before. That such a person could have a respectable career and life and be willing to risk their entire reputation, their safety and very possibly their career and freedom on a lie is a tall order.
I don't think it's impossible that someone would make up such a lie, but that all those elements would coalesce in someone willing to risk their whole world on such a lie is an improbable case.
That Kavanaugh would lie to protect his career is not improbable. That an anonymous stranger or even an actual ex boyfriend would lie under cover of anonymity is also not improbable.
I do hope that Ford is being candid. A possibility certainly exists that Ford is lying entirely, or telling the truth about the central claim but being dishonest in some of the surrounding questions.
Personally I don't think Ford's claim ought to matter anymore. As Kavanaugh's collegue recently wrote, his temperment and partisanship should already disqualify him. If Ford is found in any documented untruth, it will likely send Kavanaugh sailing through.