To make a relationship feel authentic rather than a trope, consider these elements from The Novelry and the Scottish Book Trust :
Characters should have lives, goals, and flaws that exist entirely outside of the romance. To make a relationship feel authentic rather than
Allow the tension to build slowly. Rushing the emotional connection can make the payoff feel unearned. Popular Romantic Storyline Tropes the romance lacked stakes.
Show how characters' specific strengths balance each other's weaknesses. To make a relationship feel authentic rather than
Past lovers reconnecting after time apart, dealing with old wounds.
The characters’ own fears, past traumas, or conflicting desires that make them hesitate to commit.
A believable relationship should force the characters to grow. If they are the same people at the end as they were at the start, the romance lacked stakes.