The court heard he carried out the attack after his conservative mother ‘literally drove him mad’ by forcing him to choose between her and his partner.

I believe it, actually. It makes perfect sense.

Conservative muslim mother thought her son's kuffar whore was just a sex slave. Doesn't want her grandchild to be a dirty kuffar, tells him he has to choose between his kuffar whore or her, his mother and Islam. He chooses his mother and Islam.