Old Habits: A Professor and Student Romance (Modern Spinsters #1)
Ava Guerre

Dr. Jonathan Callaghan is a man of discipline. His entire life has been a carefully managed series of choices that helped him escape the poverty of his childhood. He devoted his career to the study of mathematics – predictable, quantifiable formulas. He treats his body to the same stern discipline. His life is safe, orderly. And then he meets Cat. She's beautiful, complex, fascinating -- and she's his student. John's no stranger to self-denial, but Cat challenges his self-control in a way no woman ever has.
As the pull between them becomes too much to deny, Cat's self-destructive habits crash into John's rigid self-discipline. Is what they have real? Can they trust their feelings, or do they need to ignore their unreliable hearts?
Old Habits is a story of recovery, growth, and the power of love