So 4 years ago, the princess of some fictional country ran away, met some marine, had a fling that bore fruit, and left him 4 days later to go back to her duties. Now she's called upon him to save her, her kid, and her late sister's twins from a creep who is trying to force her to marry him.
Long separation - check
Hidden baby - check
Hero tries to keep her at arms' length. Fails. She tells him the kid is his, and goes home. He gets over his rage and comes after her. Yep; bout sums it up. Oh, there were paparazzi thrown in to force him to face her in the first place, and there was his mother who figured out instantly what he was oblivious to (the kid's paternity). And there were her parents - a princess forced to marry out of duty, and the asshole she was stuck with. The h called forth a meeting of sorts and forced her father to step down. I am trying to imagine the first two floors of Buckingham palace turned into a casino to finance the country. Can't do it.