Complex sentence: In the first part of the film, subtitled "The Pilot," Maria finds that she is in love with Vasin, but it is too late-she rejected his marriage proposal 20 years ago when he was a lieutenant in the Russian Air Force.
Split into simpler sentences: In the first part of the film, subtitled "The Pilot," Maria finds that she is in love with Vasin, but it is too late. This is because she rejected his marriage proposal 20 years ago when he was a lieutenant in the Russian Air Force.