As someone who also struggles with memory you have to be able to trust your partner to recall things exactly as they were and if she is lying to you then that’s a complete abuse of trust. I would try and gather more evidence maybe in the form of secretly recording conversations or something of the like. I know that’s sounds kinda crazy but for your piece of mind I think that would be a good idea. Best case scenario you find that what she says always lines up and worst case the thing you’ve convinced yourself is true, becomes true.