Complex sentence: Michael announces that he's leaving for good, but G.O.B. points out that he's made this threat many times before and Lindsay wonders if maybe Michael needs them more than they need him.
Split into simpler sentences: Michael announces that he's leaving for good, but Gob points out that he's made this threat many times before. Michael promises this time he's never coming back, but Lindsay wonders if maybe Michael needs them more than they need him.