A good romantic comedy has a structure something like this; Boy meets girl, there is a conflict and a resolution. Writing a romantic comedy, these are the things to think about when writing.

1. Romantic comedies is centre between two young protagonist with humour. In every romcom, the two leading characters hate each other. Giving an example from When Harry Met Sally. Harry has the view that men and women can't be friends because "sex" comes in. Where as Sally is wanting to be a journalist in New York and believe that they can be friends. They have encounters many time and they form a relationship together which turn in to a romance. The relationship of a romcom is what makes a romcom. There is when they meet, their different opinions, something drives them to be together, an obstacle comes, they break up, something motivates them to be together and they get together.
2. All romantic comedies have the same structure and plot, just a different story and different characters. For example, Notting Hill(1999) a romantic comedy following a man who works at a book shop and a famous actress, they meet each other, fall in love with each other and get in to an argument causing them to separate and they then meet again and it is now a forever. It's the same structure as Pretty Women(1998) following a prostitutes life from working on the streets to becoming a millionaire's lover. And people love these stories because it satisfise them. The stories and character are something that's not likely to happen which is why with the same plot but different story, you can make an amazing story to satisfy.
3. What motivates them to become a couple? Having a clear motivation for the protagonist to decides to lead the life as a couple with someone whom they use to have a disagreement with. Making a romantic comedy that will satisfy and is engaging for the audience. Satisfying the audience with the most unrealistic situations that will hardly happen. That is why movies like I mentioned, Pretty Women is a huge success and bought back the popularity in Romatic Comedies. Richard Curtis, a successful romcom writer, the writer of Love Actually and Notting Hill, a situation that one can say hardly happens now. It stays in us and makes us imagine being in that situation.

Romantic Comedy is another genre that has it's requirements that has to be considered and put it.