• Sit down and think about it. Why should this person break up with their boyfriend/girlfriend? Get your pen and paper and make a list. If you can't think of many reasons but just want them for yourself, you may want to scrap the plan. • Confront them about it. Start out with something along the lines of "Hey, I don't know how you feel, but I don't think Cassie is right for you." If they say they are fine with the relationship, just tell them you don't think so. If they ask why, explain. Don't push your reasoning on them. • Continually bring it up. Just say how you feel. For example, "Cassie doesn't talk to you very nicely on the phone, does she? You deserve better." Casually dropping hints about it will help the person think about it. If they really haven't gotten it, try just sitting down with them and telling them how you feel. If they accept your opinion but don't agree, at least you tried. They may think about it altogether and realize, you're right.