There is no doubt that he did it and those closest to him also knew but chose to deny it for their own reasons. When Carl insisted that he didn't remember that night, that was when the penny dropped for Marie and all the viewers at home. Carl said nothing, not out of loyalty because after all, he slept with Marie, but to stop his name from being dragged into it.
His daughter knew because of what she saw in the flashback. Perhaps as a young girl, she had a bond with her father because she was jealous of Christina getting attention from him, so clung to him? Or perhaps she was cold towards her mum because she felt it was her fault for not protecting her? I agree that the unknown/unsaid between them is eerie.
Well, I thought that was very well done and the acting was excellent.