Complex sentence: As Rachel asks Finn if Quinn had never gotten into the accident, would they be married at that moment, they meet Quinn in the hallway in a wheelchair, rolling happily and telling them that she has never been happier, because she survived the accident.
Split into simpler sentences: As Rachel asks Finn if they'd be married at that moment had Quinn never gotten into the accident, they meet Quinn in the hallway in a wheelchair. Quinn is rolling along happily and tells them that she has never been happier, because she survived the accident.