Sentence:  “I Love Lisa” opens with one of my favorite underappreciated running jokes from "The Simpsons": the passive-aggressive, quietly contentious relationship of radio jocks Bill and Marty, whose mindless happy talk regularly gives way to charged exchanges that betray the simmering resentment and disappointment perpetually lingering just under the surface of their <WSD>relationship</WSD>. 
Meaning of the word marked with <WSD> tags:  A way in which two or more people behave and are involved with each other