Complex sentence: Meanwhile, Pyle has stolen Fowler's Vietnamese mistress Phuong, promising her marriage and security, and when Fowler finds out about his involvement in the bombings, he takes one definitive action to seal all of their fates.
Split into simpler sentences: Meanwhile, Pyle has stolen Fowler's Vietnamese mistress Phuong, promising her marriage and security. When Fowler finds out about Pyle's involvement in the bombings, he takes one definitive action to seal all of their fates.