to be fair i can understand the suspicion. mainly due to the fact i'd be paranoid that shes cheating on me with someone in a hotel I paid for.
as for skype thats a bit of a distraction. i doubt shed sneak off to a hotel to skype someone. she could do that when ever. i suppose the lack of quick response is more of a worry, but then again she is there to do a job. so if shes busy shouldnt be too much of a weird thing. but it would worry me if she was delayed in talking to me when shes finished at her placement that would cause me to be suspicious.
what you could do is have a "romantic surprise".
buy a bottle of fizzy wine n some (on sale) chocolates n be like "hey romantic get away? naughty hotel time?" n then if shes not happy for you to be there (of note) coming up with reasons to get you to leave (of note) constantly or rapidly on her phone (of note). also claim you immediately need the toilet (so she cant hide any used condoms or ****) n then try to (SUBTLEY) scan round the room for evidence around the room. but dont be obvious with it. if shes totally faithful you'll just be the crazy *******. but no one can say your a crazy ******* for turning up with a romantic gift to a hotel you paid for.
And actually passed?