Who is the father in a love triangle

After giving up her career as a fashion magazine editor to build a life around Stephen and their marriage, Catherine tried to be the perfect wife. But when she found photos of Stephen getting close to his secretary, her trust shattered. Seeking comfort at Amy’s home, she drank to numb the pain and ended up crossing a line with Amy’s son, Alan, who had secretly loved her since he was 13. One month later, Catherine found herself pregnant and unable to tell whether Stephen or Alan was the father.