First off, she doesn't sound like the type of person who'd make a good and trustworthy partner just from hearing the different guy every weekend thing while working at a bar. Many people might find it offensive but I'd consider her a bit a slag to be honest. How many hundreds of guys have fucked her?

As someone who knows a lot of bartenders, almost all of them hate their job with a passion. Especially the girls. As soon as they get a degree they're looking for a new job asap. The only redeeming quality seems to be the social life (going out and drinking and taking drugs, not talking fun day trips here) and the hookups with other staff and customers. The only girls I know who want to be bartenders after university, are those who can't get a better job, or those who love the male attention - eg skanky outfits, no bras, tits out and getting hit on etc.

From what you've said, she probably falls into this category and is looking for parties and attention outside of the relationship. There's literally no other reason for wanting a bar job. There are infinitely more pleasant and higher paying 2nd jobs available that would provide social opportunities that aren't just drinking and getting fucked up.