Wedding Pictures On The Camera
What were the wedding pictures on the camera about? Maybe they dressed up that way before doing something weird. The wedding imagery parallels the girls at the restaurant getting married.
The point of it is probably to show Chris' psychosis. He got with the couple and then with the guy with the chamber. His sexual problems are the cause of his rage towards guys with more looks or money.
The wedding theme is probably present because Tina realizes that there will never be a marriage between her and Chris, just a holiday. Tina is still under the thumb of her mother, they are probably both witches, and what she did at the end was an intentional human cult sacrifice, and not a girl chickening out of a suicide pact. The site where they did it is important too, as most of the places they went were ruins and probably places of past cult ceremonies.
People think that at the end Tina started to jump and then hesitated, she was just faking him out.
The movie is really about Tina of course, that she is a witch. She plays Chris and acts like he is introducing her to evil, but she was evil all along, and setting him up for the fall.