No, Joseph and Lindsey aren't breaking up since they haven't married yet. This is about Boris and Doris, Caillou's parents, who have officially divorced due to a circumstance that transpired. According to Joseph, the only ways to keep the issue from getting worse are for Boris and Doris to refuse to speak to one other until they have resolved the matter, and to avoid exacerbating the issue.
E1 · It's Official!
E2 · Eager to Know
E3 · Interrogation
E5 · The Settlement
E8 · Off With a Warning
E9 · Supposed to Be Said
E10 · The Apology