Complex sentence: While reselecting a tree for the New Directions choir room, Rachel kisses Finn, but he stops her and says he is breaking up with her for good, since she is the second girlfriend that has cheated on him.
Split into simpler sentences: While reselecting a tree for the New Directions choir room, Rachel and Finn share a kiss. But after that, Finn says he is breaking up with her for good, since she is the second girlfriend that has cheated on him.