Complex sentence: In the end, he finished cleaning up the garage and finishing up his punishment and learned his lesson about lying and he visits Jennifer, whom he has a crush on, to apologize and promises he would never lie to again for now.
Split into simpler sentences: In the end, he finishes cleaning up the garage and finishes his punishment and learns his lesson about lying. He visits Jennifer, whom he has a crush on, to apologize and promises he will never lie again for now.