I have a cousin who does stuff for Cable TV.
The cases of talent fucking talent on shoots is through the fucking roof. And its not just talent, its anyone related to the set who is trust worthy enough to not blab. She did locations scouts for a nationwide restaurant show and realized after the fact that part of her scout for one episode was finding a place for one of the executive producers to discretely fuck the new head of catering.
A lot of B-list talent, if they have an SO their SO generally accepts that if they're away for longer than a week they're hooking up on set or the relationship doesn't last very long.
To quote her from one of the cucks "Who cares if they're banging? Its just physical and it'll be over by next year".
So I generally believe the "if they are hanging out, somethings up" - if they aren't banging, the hangouts are being used to cover up some banging.