The romance between Spencer and Alex in the Taylor Sheridan universe's '1923' is the most romantic so far. In episode 6, they face a life-threatening situation when their boat capsizes, but they are rescued by a passing ship.
To help Alex enter the US, Spencer asks the captain to marry them, and they exchange rings. The young love story of these Duttons is real and obtainable, making it the most romantic pairing on the show. 1923 is unique in bringing us some of the most loving couples in the franchise.