The most favorable way that I can interpret your girlfriend's story is that she has a drinking problem, and some of her male co-workers interpret her inappropriate drunkness on these trips as an opportunity to get laid.
In reality, I think that she enjoys hooking up with dudes on these trips and is using alcohol as a way to give herself permission to behave badly with them. And she has probably acquired a reputation for this at her company.
Good decisions come from experience. Experience comes from bad decisions.
If you want unbiased advise you'd be wise to move on.
Dump the ho; she was never your girl. I wouldn't be surprised if she'd been ****ing those other guys up to this time. You can never trust a cheater.
Sorry, she's a dud. Too much drama 3 months in. Most people are still in 'best behaviour' mode at that point. She doesn't respect herself, so she will never respect you.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh