“If You Were the Last” is game for fluffy rom-com-like tension, but it fears its own premise. What a missed opportunity.

A romantic comedy that revives the screwball formula where two people talk themselves silly — and we only had to go to the end of the solar system to make it happen.

Sappy and, in terms of its comedy, rather cringe-worthy, never quite finding the sweet spot between romance and laughs.

If You Were the Last may feature uneven humor and characterizations, but its third act provides a perfect landing that makes the shaky flight worthwhile.