Love forces characters to change. It challenges their flaws, forces them to confront their past, and highlights their strengths.
For 75% of the storyline, the characters should not be able to get together easily. The obstacle creates the heat. This stage is defined by tension—often expressed through witty banter, intellectual sparring, or forced proximity. Think Pride and Prejudice : Elizabeth and Darcy do not kiss until the final act because their pride and social prejudice literally keep them apart.