The very fact that she's flirting with someone she works with after work hours is enough to know that she doesn't have the same relationship boundaries as you do. It's inappropriate and if she didn't even offer to compromise in someway that would be acceptable to both of you then she's an attention whore who YOU are probably better off quickly getting rid of.
Dating is about finding out if who you have been attracted to will make a good, compatible LIFE partner for YOU.... obviously, she's not the one for you.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion