The conversations between rivals we see in Sense and Sensibility may be sugar coated, but even the faux-politeness of Austen's dialogue isn't enough to cover up the sting underneath. Competition (especially competition in love) is a major issue here, and somehow, the veiled nature of it makes it all the more brutal. Austen's characters are all in the pursuit of the same thing – successful, happy married life – and sometimes they're in pursuit of the same people, which makes things all the more difficult. The differing ways in which her various characters deal with the competitive nature of the world they live in reveal volumes about their individual personalities and beliefs.
Competition is a main driving force in the society Austen depicts, and its exhibition in personal relationships is simply a symptom of a larger social disorder.
In Sense and Sensibility, Jane Austen depicts competition as a primarily female trait.