10 Warning Signs For Teen Relationships
What would you do if you thought your friend was in an abusive relationship? Most of the time, violence takes place when the couple is alone. You might not see dramatic warning signs like black eyes and broken bones, So how can you tell for sure? For one thing, listen to your instincts. You probably wouldn't be worried without good reason.
Here are some signs to look for that might mean your friend is in trouble and needs your help 
1. When your friend and her boyfriend are together, he calls her names or puts her down in front of other people.
2. He acts extremely jealouswhen she talks to other boys, even when it is completely innocent.
3. She apologizes fro his behavior and makes excuses for him.
4. She frequently cancels plans at the last minute, for reasons that sound untrue.
5. He's always checking up on her, calling or paging her, demanding to know where she has been and who she has been with.
6. You've seen him lose his temper, maybe even hit or break things when he's mad.
7. She seems worried about upsetting him or making him mad.
8. She is giving up things that used to be important to her, such as spending time with friends or other activities, becoming more and more isolated.
9. Her weight, appearance or grades have changed dramatically. These could be signs of depressions which could indicate abuse.
10. She has injuries she cant explain or her explanations dont make sense.
http://www.loveisnotabuse.com/teen_10warningsigns.htm
1. When your friend and her boyfriend are together, he calls her names or puts her down in front of other people.