As much as you feel strongly about the motto “friends forever,” not all friendships manage to stand the test of time. Many go through ups and downs and are put to the test when life’s challenges threaten the relationship. If you and your friend can get through the hardships, you may have a long-term friendship worth keeping.

Disagreements and Differences

Similarities bring friends together, and differences can tear them apart. When friends realize that they no longer have the same interests, values or views on life, this can cause the friendship to fizzle out. Expecting your friends to mirror your exact beliefs and passions can cause problems in the friendship, according to friendship researcher Jan Yager in Carlin Flora’s book “Friendfluence." If you do not respect differences in your friendship and insist that your way is the right way, you may end up resenting each other.

Love Triangles

A major betrayal that can test a friendship is one that involves a shared romantic interest. When two friends fight over a girl they’re both crushing on, or when a girl goes behind her friend’s back to flirt with her ex-boyfriend, this form of betrayal can cause more than broken hearts -- it can split up the closest of friends. Love triangles involving a friend can cause blind rage in a person, which has even led to crimes being committed against the friend, according to Yager in her book “When Friendship Hurts: How to Deal With Friends Who Betray, Abandon or Wound You."

Significant Others

Even if there is no love triangle, bringing a new boyfriend or girlfriend into the mix can still cause friction in a friendship. You may feel like a third wheel, or you may even feel neglected if your friend is spending more time with her significant other. This can be worse if you do not get along with your friend’s boyfriend. Your friend may feel the pressure to choose between you and her boyfriend, which can end in resentment or the end of the friendship.

Success and Jealousy

A change in someone’s status -- whether that be by making more money, earning academic achievements or gaining more popularity with peers -- can drive a wedge between friends. Jealousy can arise if you achieve something that your friend wants for himself, or vice versa. However, the friendship can be salvaged when you realize that just because your friend wants what you have accomplished, doesn’t mean that he isn’t happy for you.