Conventions of the romance genre. Some of them never get old and still have the power to delight. On the other hands, some of them need to die a fiery death.
If your tastes run to a specific trope, pick your passion:
Amnesia | BDSM | Best Friend's Sibling | Billionaires | Boss/Assistant | Cabin Romances | Childhood Sweethearts | Class Differences | Fake Relationship | Fated Mates | Fling to a Thing | Friends to Lovers | Friends with Benefits | Impregnation Fantasy | Makeover | Marriage of Convenience | May-December Romance | Mistaken Identity | Mistresses, Courtesans, Escorts, Oh My! | Motorcycle Clubs | Office Romance | Reunited Lovers | Roomates to Lovers | Secret Baby | Small Town Romance | Smart is Sexy | Student/Teacher | Plus-Sized Heroine | Time Travel | Unrequited Love |
Villains | Virginal Hero | Weddings as Setting