His behavior changed when anyone in the lockeroom who could have checked him, left the team.
Russ would have been from the beginning who we saw when Lynch and the LOB left, if they'd never been around. And worse, Pete made sure not to bring in new personalities which challenge him. So, it gradually got worse.
Sherm, ET, Cam, etc al would never in a million years let fly Russ becoming some pseudo personality and faux 'business man' if he continued to show he couldn't read defenses.
They would have chewed his ass out. But they weren't there to keep him honest, and so he strayed and gradually spent more time 'playing' at football celebrity than he did football player.
Ciara is just his wife. Putting the blame on her is akin to the belief Pete was meddling in the playbook and bringing Russ down.
Russ brought Russ down. As the critical eyes that kept him in check left, he went full Russtard.