The short answer is that they don't. Third Brother ends up with Ren Yufei, his secretary. I really like Hu Ran and had hoped they would get back together. When Hu Ran found out about Third Brother and Ren Yufei, she became a little possessive. I was so scared of the direction that the author might take with her character. But luckily, Hu Ran turned around and realized that she only love Third Brother like a family member and held onto him because he protected her when they were married.