Cousins having a tense relationship is not unheard of. Often times this is the product of a Sibling Rivalry between their parents rubbing onto the children. Other times this has similar reasons to a Sibling Rivalry considering how close many cousins are (usually closer than other parts of the extended family). Or maybe they just don't like each other and their familial relationship cannot fix that. Either way, the cousins don't get along much of the time.
Compare to Sibling Rivalry and in extreme cases Cain and Abel. Can often overlap with (or lead to) Feuding Families. Kissing Cousins is the complete polar opposite of this trope. Contrast with From Cousin to Honorary Sibling.
Clashing Cousins has been suggested to play 2 roles. Click below to see other actors suggested for each role, and vote for who you think would play the role best.