Thrawn has a crush on Sabine that he knows very well he should not have because Sabine is a Rebel, a human, and a Mandalorian.
How can a ~40-year-old man be infatuated with a ~20-year-old woman? How inconceivable is that in our society? Like, George Lucas and Mellody Hobson? Or perhaps, Humphrey Bogart and Lauren Bacall?