A couple broke up several years ago and no longer feels any romantic feelings toward one another. This couple has a chance encounter years later, the romantic feelings start to reappear. This is an example of .

spontaneous recovery.

Explanation:

Spontaneous recovery is a psychological process that refers to the re-emergence of a behavior after a period of time. It was best researched and studied by Ivan Pavlov in his research called the 'classical conditioning'.It has been observed that these sudden re-emergence of behaviors which were thought to have extincted recover after a period of time when similar stimulus are triggered in the future.Thus, when the couple who broke up several years ago encounters years later, their feelings start to reappear due to spontaneous recovery.