My Way Back to You (Harlequin Super Romance, 1981)

Married too young, divorced too soon? 

Jeff Wells hasn't seen his ex-wife, Maggie Russell, in years. Yet as they reunite to settle their son into his college dorm, Jeff discovers the attraction between them is still present—and very strong. Yet so are the reasons they shouldn't be together… 

Still, what's the harm in giving in to their desire for a few days? No expectations, no strings. But the affair is so passionate, soon Jeff wants more. He wants what they used to have, only better. First he needs to convince Maggie this is their second chance at love and not simply a repeat of the past.