I already did. From psychological profiling.
I had this view from the very start, ever since the case was still a missing persons case.
Looking at the photos of the female suspect, and her subsequent social media posts, she comes across as cold and petty to me. She is also a heavier set person and arguably less attractive and older than the victim.
She had a worse off, less successful life than the victim, who she could have saw as just getting started with a full life ahead of her.
The family and everyone around the victim probably adores her.
I think the male suspect may have glanced at the victim a few times during family gatherings. I think the female suspect may have picked up on these cues.
Overall, all of these things could have driven the suspect to show contempt and hated for the victim. A person in that position may well manipulate the man to do their bidding. Maybe they were mutually motivated to get at the victim too.
At least, the official prosecution theory is that the motivation for this crime was sexual in nature as the suspect's shared interest in the crime. I think it was that, plus jealousy and thus contempt for the victim.