It is boyfriend, but practically it's rude expression or if you want to mock some girl's boyfriend. The same meaning is for a girlfriend, you can use ''тёлка'' :))

There's this scene in the russian crime drama БРАТ - a husband comes home after days of absence, knowing that his wife cheated on him with another guy (the film's protagonist). He beats her up and says: Я твоего хахаля, недоноска, г-но заставлю жрать! It's a nice scene 'cause the good guy is standing in the door with a sawed off, which he then puts to good use. You can find the whole movie on youtube using the title 'Брат (фильм)'. The scene is at 1:24:40

хахаль- admirer, ladies' man, fancy man ( colloquial word)

there is a story with that title by the well known soviet actor and writer В. Шукшин - "Хахаль" . I advice to find and read it . http://fanread.ru/book/1425579/ - perhaps it works over there

хахаль is usually humorous and sometimes pejorative/derogatory term for somebody's boyfriend or lover.