But what if Agnes was partly motivated by jealousy? Specifically, what if she was jealous of Theo and Lucas's close friendship? Notice how close Lucas and Theo are at the beginning of the film, with Theo being able to discern whether Lucas is lying or not and the duo often going out on drinking nights. Now look at how Theo and Agnes interact: They're consistently seen arguing, once to the point that they forgot Klara had to go to school and Lucas had to step in to take her there. Their relationship clearly has troubles if it proceeds enough to this point. Meanwhile, Lucas and Theo seem to be True Companions, always hanging out and laughing at one another. Their friendship seems perfectly healthy up to the point of the molestation accusations. Lucas also seems to share a healthy relationship with his son, whereas Agnes's son always seems to be ignoring her and Klara seems to enjoy being around Lucas more than her.
With this in mind, it's possible to interpret Agnes's staunch belief in the molestation occurring as an attempt to lash out at Lucas. While she may indeed believe the molestation occurred, she (purposefully or subconciously) attempts to push this out of an effort to destroy Lucas's relationship with Klara and Theo. He reveals her inadequacies as a mother and a wife, so she tries to destroy any chance of these relationships continuing.
- Another detail to notice is how in the ending, where Theo tries to go to Lucas's house to forgive him for treating him so wrongly, Agnes stands in the way and tries to prevent it. The whole scene comes off as if it's the climax, with the hero (Theo) overcoming the toxic influence (Agnes) that's keeping him from reuniting with his friend.