Dear Mandy,

People who behave this way are often referred to as "manipulative." A person who is manipulative tries to influence others to get them to do what that person wants. It is important to mention that we all have faults and very few of us can honestly say that we’ve never been somewhat manipulative ourselves.

People who are frequently manipulative, however, often have other underlying problems. For example, some people that are highly manipulative are very focused on their own needs and lack compassion and empathy for others. In other cases, people can appear manipulative but in fact have limited social skills and difficulty interacting appropriately with others.

Either way, it is important to let someone know how you feel if they treat you badly. The best way to do this is by being assertive. Being assertive means that you express your feelings while at the same time being respectful of the other’s feelings. For example, if a friend is nice to you just because she wants something from you and is mean after receiving it, you might say: “I understand you really wanted that, but I feel hurt that you would treat me this way. Please don’t do it again.”

Whether they know it or not, you will be doing them a big favor. People who are highly manipulative may end up having very few friends or be generally unhappy in life.

If someone continues to treat you this way, you may want to reconsider having her as a friend.