The Friends To Lovers trope is when two characters begin as friends, usually with a long-standing friendship, but fall in love through the course of the story. It's one of my favourite tropes, since it usually requires a non-alpha hero. I also love alpha heroes but they are notoriously short on friends. They might have brothers-in-arms but not someone they could call on to ask for help (which alpha heroes hate doing anyway) or talk about something emotional.
The Friend To Lover hero is usually a good guy, kind and considerate. He's been emotionally supportive of the heroine, usually through difficult times in her life. In other words, he's already put in the work that alpha heroes are scrambling to manage from the mid-point of the book onward: that they can do more than solve problems in a hail of bullets or fangs.
About a month ago, I was quite distressed to see a post talking about how the Friends To Lovers trope is actually harmful to both men and women in setting up expectations. It talked about how the trope encourages the idea of that a person can just hang around another person, doing things for them, and that eventually that other person is supposed to reciprocate by getting into a sexual relationship. The example they used to illustrate was Leonard and Penny from The Big Bang Theory.
In season one, Penny is a vivacious, attractive young woman who dates widely but is struggling financially. Leonard has a crush on her and starts doing a wide variety of things for her, giving her food, paying her bills, sharing his wi-fi, and at one point, I believe he even buys her a car. He listens to her complain about the men she's dating and is agony that she never sees him. They end up dating, breaking up, dating again and then marrying.
To me, this isn't a true Friends To Lovers story. Leonard's intention from day one is to make Penny see him as a romantic candidate. At several points in the series, he's angry about all that he's done for her and how she's failed to fall in love with him (although he does not confront her, he complains to his friends, who mock him as a loser). His friendship came with a price-tag, which to me, means it wasn't a real friendship. One can't move from being friends to lovers if they were never friends in the first place.
For a much superior example of Friends To Lovers, I'd recommend Olivia Dade's short story, Cover Me, in the anthology Rogue Acts. The heroine, Elizabeth, is in a desperate situation. She suspects she has cancer and doesn't have health insurance. The hero, James, has been her friend for many years. As he works out a way to help her, he realizes that he loves her not just as a friend, but also as a romantic partner. Although he hopes to deepen their relationship, his aid is freely offered. Regardless of how she feels about him, she can depend on him as a friend.
This is how Friends To Lovers is supposed to work. A genuine friendship deepens into a romantic relationship, not one desperate person trying to buy their way into a relationship. So, for example, I wouldn't consider Ross and Rachel from Friends to be a Friends To Lovers story, but I would consider Chandler and Monica as an example of the trope.
And I'll admit that it makes me angry to see this trope picked on as setting up unrealistic expectations. First of all, I don't think it's unrealistic for friends to develop a deeper affection for one another (a la When Harry Met Sally or several real life examples I could point to). And second, as I said before, a friendship based on an expectation of eventual sex is not a real friendship.
That's one of the things I like about When Harry Met Sally, Monica and Chandler, and Cover Me. When one character decides that their feelings have changed, they don't spend a lot of time hiding it. They're honest but don't force their expectations on the other person. There's no drawn out will-they/won't-they drama (which, by the way, is an artifact of TV scripts and not a genuine romance novel plotline). Sharing how they feel without expectations is one of the bravest things a character can do, in my opinion. And all of them are rewarded for it with solid, wonderful relationships that earn their happily ever after.
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