OP says he Got hotel room to avoid waking her and DD. hmm...
Other men seemed to go home, do they live nearer, are you further away making it more difficult/impossible for your DH?
Crying women missed her shared cab.
So..she has to get cab on her own then, seems the obvious solution, rather than, 'you can spend the night in my room alone with me where no one except us will really know whether anything happens or not and we can arouse great suspicion and gossip amongst our colleagues and caus angst with our partners, yes that seems the obvious solution'.
I always find the most worrying thing on these threads is the 'I totally trust him, he'd never do anything because he's lovely' attitude, which allows the men to behave in frankly suspicious or shitty ways without any concern.
NEWSFLASH- to the world, your husband wife may be lovely and honest, but presuming they are human they are also flawed individuals who are capable of behaving in ways that you would not expect of them, or that they wouldn't even think expect of themselves, till they do it. No one is magically entirely trustworthy, it's an ongoing process of commitment, and viligence of your own behaviour and attitudes that makes you trustworthy and as the relationships boards show this can crumble like a house of cards at any moment even for the previously 'loveliest' of people.
Athing said it best when she said (paraphrasing) ' I trust my DH because he behaves in a trustworthy manner, not because I chose to blindly believe everything he says.'
This is inappropriate behaviour both because of the implications for work and for jeopardising his trust from you. He appears to care very little, or to not understand the implications.
He's either been very foolish, or very cunning.
I'm afraid based on the info we have so far, I predict further threads over coming weeks as this is revealed to be more than the OP currently wants to believe.