Her "something old" becomes his "something new" when Alex decides that he too wants to wait until after their marriage to consummate their relationship. Carmen and Alex were brought up in different environments - financially and morally - but their love and dedication to each other transcends all obstacles.
Carmen is an only child - a change of life baby brought up by aging and ultra conservative parents who sheltered her from the evils of the modern world. As she grew into an adult, her morals were constantly being challenged. Rather than change her morals, she became withdrawn. When she fell in love with Alex, she had to address his challenges and decide which morals were outdated and which needed to be defended.
Carmen had always dreamed of being a mother. She was obsessed with the idea that a happy marriage had to include children - until Alex came along. Alex couldn't have children, but he was willing to adopt. Due to a traumatic experience involving adoption when she was young, Carmen is reluctant to adopt and Artificial Insemination is against her moral values. She isn't convinced that Alex can't have children, and she isn't ready to give up the idea that they might eventually have children.
Carmen is socially awkward and Alex is sophisticated. She is concerned about fitting into his world. She avoids telling him about anything she thinks might cause him to disapprove of her. That goes double for anything she shared with Josh, her ex-boyfriend. Josh is married, but not getting along with his wife and he shows up at the most inconvenient times.
Carmen's perception of the morals her parents instilled is putting a strain on their marriage. She is puzzled and embarrassed by the intensity of her romantic feelings for Alex. She expects them to diminish, but they get stronger. She looks for diversions, but either Alex disapproves or they don't work. Finally she finds a diversion that works when Alex's sister has twin babies. That seems to be working well when everything comes to a head. At that point Carmen realizes that she must either make some changes or lose the love of her life.
"Something Old, Something New" is the second book in author Linda Louise Rigsbee's "Carmen & Alex Series" of clean romance novels.