PARIS, Aug. 29 -- When Gigi Hadid sat down with Vogue France this week, she chose an unusual approach to a fashion magazine interview: she talked about love.

Not in the abstract sense that celebrities have long used to fill the emotional column inches between shoot credits. She talked about the specific thing she had found in her relationship with Bradley Cooper, honesty, and the specific thing it had done to her. Her friends, she said, think she looks 19 again.

"What is beautiful about my current relationship, and so different from what I have experienced, is an ability to be deeply honest," Hadid told the magazine. "To say what you think, when you think it. If that's impossible, it probably means he's not the right person."

Those lin...