Right folks looking for some knowledge

My friend(no names)is having a spot of bother at work, now his girlfriend has moved to work at a new store and having a hard time of it trying to train to get a promotion, my mate in question is doing the same thing so obviously not seeing much of eachother at the moment only when they can.
Now this where it gets complicated, one of the managers has been sending suggestive texts to his girlfriend about trying to get with her, obviously he is raging and apart from tryin to calm the guy down and tell him not to knock ten bells out the manager, i was wondering if theres any rules around the workplace about managers trying it on with staff knowing they are involved, he also knows that the manager in question has a bit of a coke habit and his girlfriend is sayin she wants space and the rumours from her work is that he is pumpin her.

So any moral responsibilty for gaffers wi the position thet are in?