Complex sentence: The sailor discovers that, as Siegel had warned him, he had been obsessed with Alice from mere sexual deprivation but unexpectedly, falls in love with Alice and indiscreetly meets her by day.
Split into simpler sentences: The sailor discovers that, as Siegel had warned him, he had been obsessed with Alice from mere sexual deprivation. But unexpectedly, Garrett falls in love with Alice and indiscreetly meets her by day.