I don't understand why so many are confused by or stymied by the dual timeline but I have my suspicions.

The key to which reality she's in at any given time is even minor attention to the detail of what she's wearing. The split screen at the start gives a big clue- in one reality she's wearing a winter white coat while in the other she's wearing a bright white coat. I won't even enumerate the many others.

The movie was cute and I didn't hate it but it was another mediocre Hallmark by the numbers romance they work into everything (over-achieving, over-dressed women, frequent , very long commercial breaks, etc.) complete with the picture perfect ending.