The love story was meant to be love at first sight, but if you want to rationalize it: Chris loved Kim because she was the first innocent thing he'd ever seen in Vietnam, and because like many American boys he had a "damsel in distress" complex. Kim loved Chris because he represented her way out of Vietnam.
You have to think about it through Chris's eyes; he tried to find Kim and couldn't, and it's also understandable why he never told Ellen about her. As for Ellen, she isn't meant to be a villain. No one's meant to be a villain, not even Thuy.
Btw, if you think Chris is bad, check out his "predecessor," Benjamin Pinkerton.
Jimmy, what are you doing here in the middle of the night? It's almost 9 PM!
Updated On: 6/28/07 at 12:14 AM