You might not be an expert, but any true friend will offer advice to a BFF who is in a bad relationship. Unless your friend needs professional help for a serious situation such as abuse, you can step in and offer your words of wisdom. Think about your own relationships and use them as cautionary tales or a road map to success as you help your friend.

More Than a Little Respect

If your friend is feeling slighted, remind him that there are two people he needs to respect in his relationship: his partner and himself. When one person puts down the other's beliefs, values or opinions, the clear lack of respect can ruin the romance, according to the article "What's Your Relationship Reality?" from the Stayteen.org website. If his girl is knocking his ideas, tell him to speak up and confront her about it. Doing so may get him the respect that he deserves from his partner as well as from himself.

Trust Builder

If you're constantly hearing, "I think he's cheating on me," it's likely that your friend doesn't trust her guy. A lack of trust can quickly lead to a bad relationship that is filled with jealousy. While it's normal for your friend to feel a pang of jealousy when her boyfriend talks to a cute girl, making wild accusations or stalking him isn't. How your friend reacts to jealousy-provoking situations shows her level of trust, according to the article "Am I in a Healthy Relationship?" on the TeensHealth website. Provided your friend doesn't have a real reason to not trust her boyfriend, advise her to let go of the jealousy and realize that she's the apple of her man's eye.

Honestly Speaking

Like trust, honesty is one of the building blocks of a healthy relationship. If your friend's bad relationship is a result of his dishonesty, speak up and tell him that he needs to turn around. While you might want to always back up your best bud, true friends tell each other the truth no matter what. For example, your friend tells you that he's super stressed because he's cheating on his girlfriend. He can't handle the guilt and is picking fights with his girl as a result. Sit him down and have a conversation about honesty. Explain that he needs to come clean, even if that means his relationship will end.

Find Help

There are times when you can't help your friend out of a bad relationship. If your friend is suffering from dating violence -- whether it's physical or emotional abuse -- you need to point her toward an expert. Dating violence can include hitting, punching or other physical acts as well as stalking, making threats, shaming or isolating the other person from family or friends, according to the U.S. Centers for Disease Control and Prevention. When a friend is in an abusive relationship, tell her to end it immediately and talk to a trusted adult for help. Suggest that she go to her parents, a teacher or a counselor for advice, or try a hotline such as the National Dating Abuse Helpline or the National Domestic Violence Hotline.