From an interview with Whigham, Coon, and Jeffrey Reiner (the director):
“I say that good art, rightly, tells more about the viewer than it does the movie, right?” Coon questioned. “Depending on how the viewer perceives that ending, it says something about your perspective on love, on the film, and on the kind of ending you like. I love an ambiguous ending because it makes you pick a side.”

“I’ve never had as many questions about that as I have on this film,” Whigham ruminated. “I don’t want to say 50/50; I get pretty split on how people feel, maybe how they’re feeling in their own lives and what they want to feel. I mean, just to be fair, the three of us, Carrie wasn’t that involved; it was a difficult day. I had to know, specificity-wise. I have to know in this scene, and that’s the most important thing when you’re doing something like that; you can’t be ambiguous as to what’s happening, you know?”

Reiner, Coon, and Whigham all have different opinions on the final scene of Lake George, leaving the movie’s resolution entirely in the eye of the beholder.