"Problems that are abstract, remote, trivial, ordinary, easily overcome and/or happening for someone for whom we feel little cannot fuel a gripping novel. Conflicts that are deep, credible, complex and universal so that a great number of readers can relate are in the breakout novel. Make conflict deeper, richer, more layered, more unavoidable and more inescapably true."
-- Donald Maas, Writing the Breakout Novel
In a romance, there are two basic kinds of conflict.
An external conflict is a problem that doesn't stem from the character's personality and/or past. It's a "real world" problem (like a war or conflict between two businesses) and springs from the characters' individual goals.
In a romance, the external conflict provides reasons for the hero and heroine to stay away from one another, but it also provides reasons for the hero and heroine to continue to encounter each other. External conflict both thwarts and encourages the romantic relationship.
An internal conflict comes from within the character, based on problems and issues stemming from his or her past that creates trouble for them when dealing with other characters.
In a romance, internal conflicts provide reasons for each main character to believe the relationship isn't viable -- it wouldn't work even if the external conflict didn't exist.
All internal and external conflicts have to be resolved in a way that feels satisfactory to the reader at the end of the book. In a romance, that particularly means that the reasons the hero and heroine believed prevented their relationship have been overcome.
Because conflict is so important, have as much as you can. Here's a general rule of thumb: at some point in your novel, your main character(s) should be in conflict with every other character in the story.
"If the plot is simple, the stakes had better be high, the characters complex and the conflicts layered like a wedding cake." -- Donald Maas, Writing the Breakout Novel
How do you make conflict "deeper?" What does "layered" mean?
Both mean the same thing -- don't settle for the easy, obvious conflict, and don't settle for one. Especially in a romance, which is focused on a relationship and emotions, the internal conflict -- the reasons the course of true love doesn't run smoothly in your novel -- should be like layers of an onion. There can be the obvious, but beneath it are other issues, past hurts and dilemmas to be explored.
An Example of "layering" of conflict:
(Note: This basic story is beyond cliched!)
The hero owns a construction company that has bought land on the coast to build a resort; the heroine wishes to preserve the natural habitat. They meet over this issue, and their opposition to provides the external conflict.
However, because this is a romance, two other things must happen:
1. The hero and heroine must be attracted to each other. 2. They must have personal reasons for not acting on that attraction, beyond the external conflict.
The heroine is determined to save the wetlands because she values nature. However, the resort will provide some much needed employment to the area, as will the construction of the buildings. The hero is determined to prove to his father that he's capable of completing this huge project and saving the family company; nevertheless, he also realizes the value of the wetlands.
These are two internal conflicts based on the external. Now let's add some more.
The heroine caught her last boyfriend cheating on her. She now has serious trust issues. The hero seems like a nice guy, but maybe he's just trying to use his charm to trick her into giving up the fight. After all, you can't trust men.
The hero is never sure if women value him, or his money. His last girlfriend proved to be nothing more than a gold-digger, despite her vows of devotion. The heroine doesn't seem to care much about wealth, but maybe she's trying to use her charm to persuade him to move the resort. Women can't be trusted, after all.
This conflict comes to the fore whenever they're alone and creates sexual tension.
The hero's bank is getting nervous about the situation and might cancel the necessary financing.
The heroine's boss is upset at all the time and energy she's putting into her "nutty" cause.
The heroine has a friend who desperately needs a job and doesn't want to leave her family, who live in the area. If the resort is built, there's a good chance she can get a job and stay.
The hero has a friend who believes the hero will never measure up to his father's standards, because Dad is an unreasonable bastard. Why bother trying to prove yourself to him?
The construction company headquarters is bombed. Friends of the heroine, or the heroine herself, may be involved.
The hero and heroine have both recognized the attraction and acknowledged it (at least to themselves). By now, they've each learned more about the other's past, so they have a greater understanding of what's at stake for each other if the initial goal isn't met. Perhaps they've acted on their attraction physically.
Both now realize this relationship is different -- more intense, more serious -- from previous relationships. They may be falling in love.
The hero, however, has been taught that love makes a man weak and vulnerable, and especially given the situation with his company, weak and vulnerable are the last things he wants to appear to be.
Also, if he gives in to what the heroine wants (i.e. giving up the construction site), how will his father judge him? He desperately craves his father's approval.
The heroine secretly fears her boyfriend cheated on her because she wasn't "woman enough" for him. An outwardly self-confident woman, she was a nerd in high school -- never the belle of the ball. She remains insecure about her attractiveness, and finds it hard to believe that a sexy, wealthy man can really want her.
Although she's now in love with the hero, the heroine feels passionately about preserving nature for future generations because her family lost their farm when she was a child, and her parents never really recovered. Her father wound up in a dead-end job, her mother sank into depression. This has also contributed not just to the heroine's urge to save the wetlands, but also to her deep-seated feeling of unworthiness -- she wasn't enough to save her parents. Admitting this insecurity requires trust; can she trust this man with this intimate revelation?
The hero reveals his past experiences as the son of a tough, hard-driving businessman, and his feelings of loneliness and abandonment. Like the heroine, he felt he "wasn't enough" for his father. This shared insecurity is another way to bring them together and deepen the relationship. Since he, too, is insecure and fears revealing that "flaw," it's a measure of how far their relationship has progressed when he tells her.
For me, it is this shared knowledge and understanding of these hidden fears and insecurities that makes a lasting relationship between a hero and heroine truly believeable, because it's based on shared emotional understanding and empathy far more than physical attractiveness or simple desire. The attraction and desire brought them together, but it's the deeper emotional understanding and empathy that will keep them together for the long haul.
However, in some romance novels, the hero apparently has no insecurity. He wants the heroine, he goes after the heroine, he gets the heroine, without ever once questioning whether or not she might have a very valid reason for rejecting him. This, to me, makes for a less interesting, realistic character and relationship, but there are plenty of readers and writers who like their heroes pure alpha male.
But on with our story.
The why and how of the revelation of the depth of their true feelings usually depends on the external conflict -- something from the external conflict forces the revelation.
The perpetrator of the bombing takes the heroine hostage. He wants her to persuade the hero to come to their location, with the obvious intent of killing the hero. If she doesn't, he'll kill her. The villain has also wired the building they're in to blow up if anybody tries to force their way inside, even though that will also destroy the natural habitat, because his motive has nothing to do with nature and everything to do with personal vengeance.
The external conflict has provided the catalyst for the crisis and the black moment, which is when the relationship seems doomed. The climax is the event that brings about the resolution of the crisis (in this case, it would be the confrontation between the villain, the hero and the heroine). In a romance, this is also the ultimate test of the relationship as it's been established in your story.
For your story to be ultimately satisfactory, all the conflicts, both external and internal, must be brought to a satisfactory and believable conclusion. All the subplots should also be resolved. When it comes to a romance in particular, the reader must also believe the hero and heroine have achieved a long-lasting, committed, loving relationship. If they "dropped in" on them ten years from the end of the book, they'd still be together and happy.