this is why you don't rush into things. I've known people who get married after a few months and they are very happy and it lasts for 50 years (I actually know people in their 70s and 80s who have done this) BUT in general I'd say - for both men and women - take your time. it helps if you have female friends or sisters. If they are loyal to you and don't like your girlfriend - there is a reason!
My brother broke up with an incredibly sweet girl who would have made a great wife, but she wasn't pretty enough for him. He married a gorgeous gold-digger instead. I warned him about her.... we'll see how he makes out in the divorce.
Oh, BTW, the same holds true with men. I make sure the guys I date meet my best guy friends if it's getting serious. If they don't like the guy - I take that seriously. Men can pick up on things women can't, and vice versa.