DH working away - unfaithful?

[CommonBlackbird]

I've NC because I don't want this linked with my profile, and I'm asking on behalf of a friend who doesn't use Mumsnet.
This might be long as I don't want to drip feed.
'Luna' is 26 weeks pregnant (yay) but her husband has started to work away more frequently. He works 'away' in the UK and it's true (has worked away sometimes before!- it isn't all of a sudden) but it's now 2/3 days a week.
There's been a 'change' in how he is with her, not as affectionate and more distant etc, but she can't really prove this??
I suggested it may be because of baby and he's worrying/ freaking out (I'm not excusing his behaviour, because it isn't acceptable) but she thinks he might be cheating on her, when he's away with work.
I've told her to just ask him but she doesn't have any 'evidence' and if he is cheating she wants to 'get her ducks in a row' with finances etc before the baby comes.
Is there a way she can find out discreetly (without having to travel to the hotel) to see if he is being unfaithful? The hotels vary across the UK (but he stays in the same hotel in that area every time).

What do you expect us to say?

Any other signs?

I think if she really does think he is being unfaithful she should ask (or pay) someone he doesn’t know to spy on him at one of the hotels. I know it’s drastic but then she would know for sure.

What sort of job does he do?

If she suspects him of cheating then there’s no trust so the relationship is likely over anyway.

He could just be stepping up now he’s going to be a father and working more or he may not be as happy about the baby as she is. If it’s really a “friend” you only have one side of the relationship.

Do they have joint finances? Or can she access his finances? I would start there to see where he is spending his money. Meals out etc

Maybe he is working more hours because there is a baby on the way? In what ways is he being different towards her? It is impossible for us to answer

Does 'LULU' know why he's started working away more? Is there a change in work? It may be he has other things going on that are taking his attention (not necessarily an affair). He could be generally pissed off about the changes to his work and thats spilling over. She could simply ask whats happened that he needs to be away so much now.
Perhaps he is having an affair, perhaps he isn't, sitting worrying and nursing suspicion is probably just as damaging to her relationship.

Private investigator?
Or ask a MNer near the hotels where he’s staying