In the Typical Long-Term, Romantic Relationship, a Couple Will Experience

In the typical long-term, romantic relationship, a couple will experience passionate love for ____.

A) 3 months or so-6 to 9 months at the most
B) a year or so-2 or 3 years at the most
C) 7 years or so-10 to 15 years at the most
D) an unlimited number of years or decades, if the relationship is successful