Monkeyitis

Noun - Pathology.

A reoccurring ailment characterized by the attraction to members of the opposite sex who are not available for a relationship.

Also noted for its incredible difficulty to be cured.

Origin - 2000s; English: Monkey + itis.

"What happened to that girl you liked?"

"Yeah, well, it was going well until 'Monkeyitis' struck again"

"Ah shit man, that's tough".