This song describes the optimism I had in my first relationship.
The first verse describes uncertainty about whether or not my partner and I would remain together due to our differences. Then, the chorus brings forth a sense of hope, as despite our differences, we knew we wanted to have a future together.
The second verse implies our history--the struggles we had gone through together and separately. All the moments of trouble were "markings" in our lives that we could move on from and forget.
There were several instances where we felt like other people were rooting for our "downfall." Therefore, the bridge motivates those people in our lives to continue saying whatever they want to--because, at the end of the day, we could still dream that we would make it together. When the chorus is repeated, it re-introduces the hook: "Calculate our chances" in a more positive and sureful way. In other words, it highlighted how there were no more doubts that we could make things work.