Your inkling that something is wrong in the relationship is probably right. By nature of being a woman, you have a keen intuition, so you'll feel any kind of distancing on a visceral level pretty quickly. And unless you're an overly suspicious or insecure person -- you know who you are! -- you should always trust your gut. Example: He's incommunicado. Before the days of emailing, texting, IMing, and Facebooking, if you didn't hear from your boyfriend for a day or two, it wasn't the end of the world (or your relationship). But now that communication is so easy and instant, it's usually a sign he's not fully invested.

"When a guy wants to break up, he'll often start to create space," says Oikle. In other words, he'll stop calling quite as much, it will take him a bit longer to return your texts or emails, and he'll sometimes be "too busy" to hang out. "For the record, if a guy is into you, he'll never be too busy," says Paul Coleman, PsyD, author of "The Complete Idiot's Guide to Intimacy."

If the pattern continues, confront your man about his behavior in a direct yet nonaccusatory way, saying something like "You haven't called me, and I'm thinking that means you're having second thoughts about us." If he doesn't give you a clear answer, well, let's just say he's giving you a clear answer.

If a man has a history of cheating on his girlfriends, he'll probably cheat on you too. Sometimes a guy cheats on his partner because there is an emotional or physical void in the relationship. But more often than not, philandering is indicative of something wrong with him. According to Jay Carter, PsyD, author of "Nasty Men," many guys two-time because they love the thrill of the chase, they need to feed their ego, or they have a hard time turning down a woman when the opportunity presents itself.

All those factors contribute to serial straying, "which is why men who cheat once usually cheat again," says Oikle. (A recent MSNBC.com survey found that men are twice as likely as women are to cheat more than once.) So if your guy cheated on his last girlfriend with you, don't necessarily write it off as an isolated incident.

If a guy tells you that he's not ready for a relationship, take his word for it. Believe it or not, men really hate to disappoint women. So if he's "gotten up the guts to actually cross the threshold and tell you that he's not ready for a relationship, he means business," says Oikle. There could be a variety of explanations for his antirelationship position (he has commitment issues, he wants to meet other people, he doesn't see you as girlfriend material), but in the end, the result is the same: He's doesn't desire to be your boyfriend. End of story.

And no, he won't change his mind when he gets to know you a little better. "Once a guy decides how he sees a girl in his life, it's hard to break out of that thinking," says Coleman. Warning: If you stick around after he's told you this, he will likely take it as a sign that you're cool with the casual, nonexclusive nature of your relationship. So make sure you are.

You won't regret breaking up with a guy you're feeling unsure about. Nowadays, women may be impulsive about dating guys but not dumping them. "In fact, a lot of single women will try really hard to fit a square peg into a round hole because they want the relationship to work so bad," explains Magids. "It's only after a tremendous amount of thought and effort that they finally give up on it."

In part, women go through that painstaking process because they fear they'll end up kicking themselves for ending a relationship too soon. But a new study from Northwestern University found that even in the short term, people aren't as upset as they thought they'd be after a breakup. So if you sense you're with the wrong person, don't fret so much about walking away to find a better mate.

You will always be the one to initiate a relationship talk. Unlike women, who are conditioned to take the pulse of a relationship from time to time, men don't contemplate the state of your union until something's wrong. And even then, they want to work it out in their mind, whereas women want to talk it out.

When you go to initiate a relationship talk, bear in mind that men are uncomfortable with the unknown and paranoid that you'll end up in tears. So don't ambush him or it'll feel to him like going to the principal's office or being pulled over by a cop: surprising and nerve-racking, says Coleman.

To put him at ease, try what Oikle calls a compliment sandwich: Start with something positive, work in the concern, and end with something positive. For example, if you're trying to gauge if a new guy sees your relationship as serious, say, "I really like you a lot. Are you thinking this is a long-term thing? We've been having so much fun that I hope you do!" That will be much easier for him to digest than "Hey, am I your girlfriend or what?" Or if you want to broach the subject of moving in with a dude you've been dating for a while, try "I think we have an amazing relationship, and I'm ready to take the next step and move in together. Think of how much fun we'd have living under the same roof!"