Relationship
The amount of relationship points two Sims have for each other determines how they can interact. When Sims interact with each other, they build daily relationships. Over time, two Sims overall relationships will build up as long as they continue to interact.
Relationship Levels
Enemy - -50 daily points or below (?)
Friend - 60 daily points or more (?)
Crush - ? when doing romantic interactions (kiss, flirt, etc.)
Best Friend - 75 daily points or more (?)
Love - 75 daily points or more (?) when doing romantic interactions (kiss, flirt, etc.)