As I talk about in my new book, Was it Something I Said?: The answer to all your dating dilemmas, the proof is in the pattern. You have to allow enough evaluation time to pass in order to truly see a man's character. That means not screaming foul at the first sign of a wink and a smile.
Matthew Strickler, a Senior Contracts Manager, dodged a flirting accusation early on in his relationship because his then girlfriend (and now wife) knew he was a good guy. "I was friendly with a bunch of her friends at a party we co-hosted once. I wasn't risque or overtly flirty ... I was just trying to make everyone feel comfortable and help with introductions. Later I find out that my girlfriend's best friend tells her I was flirting and touchy-feely with every woman in the house. I thought, "Wow. What?" To be guy-appropriate I'm supposed to sit still, drink my beer, and shut up? Bad standard when most women I know say they wish their fellas would open up a bit more."
The lesson is clear. Being friendly towards girlfriends is not the first sign of danger. Even if a guy is being a little flirty, it does not mean he is going to be unfaithful, and most of the time, it is that very fear that causes women to overreact to friendly behavior. Unless your man is overly flirtatious on a regular basis, there's little need to whine or worry. Observe him over time and don't make snap judgments. You have to give your guy a little room to breath, or else you just may suffocate him.
Now, if you have found your guy to be in constant contact with a friend or an ex, that is a whole other story. Find out how to approach him about it the right way, so you can determine if he's still worth your time.