My boyfriend brought his cousin to dinner with me. Should I go? His cousin has never liked me very much and hasn't said a few words.

You should go. First, give your boyfriend a face. Second, if you mean it, face it bravely. Third, his cousin doesn't like it, because you don't have much contact, so you are not familiar with each other. When facing his cousin, be natural, gentle and generous, and make way for his cousin everywhere. As long as you treat it sincerely, you will get along in harmony sooner or later.