Time Upon Time - Time Upon Time Series, #1

A man on a quest to save his relationship with the love of his life takes a trip with his best friend only for the two of them to end up whisked away through a portal in time. Here they not only learn that every action or decision could have grave consequences for their own future, but they stumble into a mystery as old as time itself, and end up on a mission to not only save themselves but the very future of humanity.