Mixing business with pleasure! Brad Pitt has turned to girlfriend Ines de Ramon for help in building a lifestyle empire, blabs a source. In September, the actor, 59, launched a luxury skincare line, Le Domaine, but that was just the beginning. “Brad has multiple ventures — jewelry, clothing, home, textiles and more. It’s a global brand with a lot of foreign partnerships,” says the source. “Ines is working with Brad on many of them. She has a strong background in fashion, sales and marketing.” The 32-year-old jewelry exec is also proficient in five languages, including French, German, English, Spanish and Italian. “Brad is very serious about these businesses, attaching his name to them,” the source continues. “He knows that people may not take him seriously, but he is very passionate…