In a Holidaze by Christina Lauren

 If you're just in the mood for happy fluff, check out Holidaze.  It's an annual tradition for 20-something Mae and her family (divorced parents, younger brother) to spend the Christmas holidays in the mountains with another family, which has 2 hot sons (Theo and Andrew). Mae has had a crush on Andrew for years, though he is completely oblivious. One Christmas, after too much eggnog, she has a makeout session with Theo, which she totally regrets the next morning in the cold light of day. As the family is heading home after the holidays, they're in a car crash. But when Mae wakes up, she is instead on a plane with her family heading to the Christmas cabin--because the week hasn't happened yet. This keeps happening to her and she can't figure out why. So she decides to change what happens--and tells Andrew how she really feels about him. Comedy ensues. As does romance. It's a cute story and a quick read.