Once, I had this question: What are the potential uses of romance between characters in a fictional story?
After reading a book(which I shall not name to avoid being accused of advertising), I got a great idea for what just might be the best use of romance in stories.
Your character will have some kind of weakness that is runing their life and making it hard, if not impossible for them to accomplish what they want to do. This weakness leads them to take stupid, often unforgivable actions that become worse and worse. As a result, other characters, usually allies, begin to point out the character's flaw in his thinking. Eventually, he either realizes that he's wrong and changes his ways or doesn't listen to his allies and is destroyed.
How does romance fit into all of this? Easy! I have found that one way to make the allies criticisms more intense over time is to make them come from allies that mean more and more to this person, eventually leading up to the protagonist's romantic partner pointing out his problems, making him change. This can be a good way of explaning why he accepts the criticisms now, but didn't do so earlier.