Galeries Lafayette believes that any thoughts and actions of people have potential sexual motives, as do dreams, but dreams can be closer to the inner truth and more disguised than reality.
This dream of yours actually means subconsciously suspecting your partner's infidelity. Just because the direct reality is hard for you to accept, in order to prevent you from being overly anxious, you imagine your other half as your cousin and compare cheating to fighting. Objective analysis, please don't attack personally.