Complex sentence: She starts dating Paul's co-worker Myk, and gets engaged to him, but then Paul reveals that Myk is in the country illegally, and might be only marrying her for a green card.
Split into simpler sentences: She starts dating Paul's co-worker Myk, and gets engaged to him. But then Paul reveals that Myk is in the country illegally, and might be only marrying her for a green card.