“Here was the trouble with navigating cystic fibrosis: no one we knew had been there, no one could tell us what to do. And here was the great thing: no one had been there, no one could tell us what to do,” writes Elizabeth Scarboro in “My Foreign Cities” (Liveright, 296 pages, $24.95), a graceful memoir about her life with her first husband, Stephen Evans, and the third member of their young family, cystic fibrosis.

Cystic fibrosis (CF) is an inherited chronic disease, and when Evans was diagnosed only 50 percent of children with CF could expect to live longer than 30 years. Scarboro and Evans met in high school, when Scarboro could see only a glimpse of the health difficulties and personal challenges of Evans’ disease. They continued their long-distance relationship through college, and Scarboro knew she had to make a decision: Should she take advantage of her youthful freedom and travel the world, or would she move to San Francisco to live with Evans? Scarboro writes, “In comparison to Stephen, most things would be there. If I wanted him, I had to hurry up.”

So, as they hung out with friends and in bars, like twenty-somethings do, they also spent a lot of time in the hospital, a place where “illness was ordinary.” They married and moved to Boston so that Evans could attend graduate school, and optimistically Scarboro hoped to find a change of routine and a “thick foreign landscape that swallowed us and kept us feeling alive.” They knew they couldn’t escape CF, but they could at least keep it guessing.

After the death of Evans’ father, Evans’ painkiller addiction, and the realization that Evans would need a double lung transplant, the couple returned to the Bay Area for the surgery. While they had become familiar with the ups and downs of CF, “The country of the transplant was a strange, underwater place.”

When Evans left the hospital after the transplant, he felt a new life unfolding, one where he could breathe, but he soon discovered that the transplant also exacted its high price — he experienced weight gain, impulsivity, forgetfulness and a multitude of other side effects from the 30 different medications he needed to take. Scarboro soon experienced her own breakdown as CF took its toll on her as the caregiver.

Ultimately, a virus wound its way into Stephen’s new lungs, and within a couple of weeks Scarboro found that she was a grieving 29-year-old widow; it was a new country that she had to explore alone. “My Foreign Cities” treads lightly, but attentively, through the landscape of disease, but more important it explores the ability to love someone passionately with no regrets.

Meganne Fabrega is a freelance writer and a member of the National Book Critics Circle.