There are rumors to this effect. And worse. Unconfirmed. Remember, it's a very small town. Everyone knows everything. "claudianunes, post: 15146857, member: 219523"]The text messages Riley sent to her boyfriend on the night before her disappearance, about mom's boyfriend being in her bedroom and about her being scared of him being there, makes me think that there as sexual abuse or, at least, actions leading up to sexual abuse prior to that night. And, to me, this might mean that a) she was threatening to tell her mother about it for a while and he was on edge, got violent and killed her so she wouldn't say anything; or b) he was indeed making sexual advances on her and, she was resisting and fighting it, and he got violent and killed her.
If she was being sexually abused, she most likely told her boyfriend about it. I don't know about telling her mother, but it's also possible that she told her or was meaning to do it.
Regarding the issue of mothers not believing their daughters when stepfathers and boyfriends abuse them is actually very common. And, if they do believe them, it's also common for mothers to think that their daughters are at fault for the abuse. Which, honestly, is insane and I just can't understand. That is the ultimate betrayal from a mother to her daughter, and it's disgusting.