
Why was the dad in the trunk in the first place? Did I miss something???

He gathered up some kind of cleaning supplies - I think he was in the trunk cleaning it to remove any evidence. He felt partly responsible for his kid doing something bad, but like an idiot he decided to help them cover it up instead of...I dunno...punishing his murderer or a son. He had no idea they would 1) try to go out that night, 2) instead of looking in the trunk they just slammed it shut and, 3) they pushed the car into a lake.
I don’t care how long it takes for the second couple to get together because the more time spent on them the less drama the first couple has to deal with and the lack of drama with them is why I love this so much