- Being a user.
No ride home? He'll be there in a second to pick you up. Running out of cash? He'll surely treat you for lunch. Math homework too hard? He'll stay up late just to help you solve it. The guy is your 24-hour helpline. He likes you—but you only like what he can do for you.
The verdict: Your anthem can be that old Britney Spears hit: "Oops! I did it again. I made you believe we're more than just friends." Shane, 22, confesses, "Sometimes, I want to see how far he will go. I feel important seeing him running after me."
How to deal: It's better if you tell him upfront that you're not interested, rather than mislead him into believing you'll reciprocate his feelings. If you prolong this, it will be much more painful for him once he becomes aware you were just using him.
- Snooping through his things.
While using your boyfriend's laptop, you check your Facebook account but find him still logged on. You sift through the contents of his page, and before you know it, you've got your prying eyes on his e-mail messages and other files as well.
The verdict: He may be committed to you, but he's still entitled to his privacy.
How to deal: "Spying" on your guy—whether snooping through his bag, phone, or computer—can indicate a lack of trust. Even if you're suspicious of what he's doing (you want to know if his ex still texts him), you have to respect where he draws the off-limits line. Rather than invade his privacy when you want to get information, just ask him directly or get his permission first.
- Flirting with other boys.
While sitting alone at a party, your long-time crush walks up to you and chats with you. The next thing you know, what was supposed to be a casual, friendly conversation morphs into an exchange of romantic banter.
The verdict: While flirting can be fun, it's a no-no for girls who are already committed or going steady with guys they are dating.
How to deal: You may think it's harmless because you're just playing around or testing the waters, but your guy can be offended and find flirting unacceptable. To gain back his trust, avoid being caught in sticky situations. You can choose not to entertain other guys' advances, too.
- Fencing yourself around him.
This is almost similar to Case #2, except that you act as a bodyguard instead of a spy. No one comes close to your guy without your approval. You join him during breaks, attend his basketball practices, and throw dagger looks at all the girls who come near him.
The verdict: You limit his opportunities to get to know other people, improve his talents, and become a better person.
How to deal: While you can tear down the walls you've built around him, you have to first address what could be your trust issues against him. He might choke on your constant presence and ask you to back off. If he assures you there's no reason to doubt him, why don't you give him some space?
- Cheating on him.
Beyond actual cheating, you can also cheat on your guy emotionally. "I think it's possible to love two people at the same time," shares Krissy, 22. "I had a boyfriend, but I was also emotionally involved with someone else. I knew I was being unfair to both of them."
The verdict: For most guys, cheating could spell the end of the relationship. Think of it this way—if the situation had been reversed, would you forgive him?
How to deal: Be willing to face the consequences. If your guy wants to break up with you, understand that you've hurt him badly. If you want to win him back, it may take a while for him to recover but be patient. If you've made up for your mistakes, he may be willing to give you another chance.
- Being mean to his ex-girlfriend.
A date at the park with your guy is going perfectly until a familiar face shows up—his ex! Your mood suddenly changes and you blurt out, "She put on some weight. And what's up with her hair? She should ask her salon for a refund."
The verdict: Criticizing his former flame might boomerang on you as it exposes your insecurities. "Pointing out the faults of his ex-girlfriend used to boost my self-esteem. I thought it would make me feel better, but I felt otherwise. It only showed how insecure I was," says Geline, 21.
How to deal: Instead of focusing on her hits and misses, why don't you focus on what you and your guy share uniquely together? He probably wouldn't be with you if you weren't the best girl for him, right?
- Being the "other" girl.
He has a girlfriend but he's also dating you. "I knew it was wrong, but he told me to hang on. He was just waiting for the perfect time to leave his girlfriend," says Abby, 20, who later regretted allowing herself to become the "other" girl.
The verdict: Being involved with an attached guy is risky, so prepare yourself for a rollercoaster ride of emotions. Aside from him not prioritizing you and keeping your relationship a secret, you could also be on the losing end if he chooses his girlfriend over you in the end.
How to deal: Confront him and tell him that if he is serious about you, he should muster the guts to tell his girlfriend he found someone else. On the other hand, if you realize that he should stay with his girl, be the first to turn down his advances and get to know other single guys instead.
This article was originally published in the July 2010 issue of Candy Magazine.