Just because they end up with the love of their life doesn't mean that they are great, as some romantic interests are actually terrible people. Romances have always been an integral part of storytelling. There's an entire genre of films dedicated to the topic, that even gets broken down into different segments depending on the movie's overall narrative. Even in other genres such as action-adventures and thrillers, there's still usually a love story that simultaneously develops alongside the main plot.
https://screenrant.com/movie-love-interests-terrible-people/