2 people with no reason to lie (at least none that makes sense to me)
Sociopaths rely on the fact that normal people are not so brazen about lying. Most people wouldn't contemplate lying so brazenly and casually, so they don't imagine others doing the same. This benefit of the doubt is what allows sociopaths to be superficially charming, when you don't care about the non-immediate consequences of what you're saying, you can impress people much more easily.
"They have no reason to lie" is faulty thinking when you're dealing with someone you don't know quite well whom you can trust implicitly. Anyone else who makes accusations, you should expect evidence. Benefit of the doubt should not extend to impugning others.
As i said immediately after the sentence, the burden of proof is on fyrst. Because it would be unreasonable to ask heidi to prove a negative.
The sociopath thing could apply to either one. Im not saying either one is or isnt, but its he said she said, and I don't know him or her.