Okay, so now you have your couple, and you have built them as a couple. Now you need to bring them together. This in and of itself is going to require a little finesse, but not much. Like pretty much everything else, you need to look at like a basic three-act play: First they are going to meet, then they struggle, and then things start working out. Sounds easy, right? Well, not for them…
There are two basic approaches: They are already in love but Fate conspires against them, or they hate each other and Fate conspires for them. Romeo and Juliet typifies the former approach; they have a number of obstacles to overcome in order to be with each other. Those obstacles can be friends who don’t think that they should be together, family obligations, physical issues such as distance or actual barriers, or even legal problems such as one is incarcerated or one is stuck outside the country. There can also be social issues, such as separation by caste or membership in opposing factions. This also includes reason such as age or gender problems. These obstacles need to overcome in order for the couple to be together.
Usually the obstacles are overcome by the male as an effort to prove himself to his lover, but the female can also be the one. This is best for when the romance needs to move on to the next stage relatively quickly, as there is a defined goal that needs to be dealt with and that goal usually holds something else up. At the same time it can be extended indefinitely in order ensure that there is an ongoing plot. Although the latter method is usually better for maintaining sexual tension among the audience, this is better for maintaining sexual tension among the couple; they never know when the situation will be resolved, and until it is it will be between them. This is also great for comedic purposes, as they can be meeting but if they were ever found out there could be severe consequences, such as two gay lovers in a homophobic society.
The latter case is more aggravating as it takes a little more finesse. The obstacle is simply that the couple hates each other, and they need to overcome that hatred to become an actual couple. Eventually the grudge will become grudging respect, and then compassion and then true love. The relationship can move up and down this scale, of course, especially after they have fallen in love; it could even be that the relationship depends on that mobility, ranging from respect to hatred even on an hourly basis. In a way this is a deeper relationship than the former, as it comes across as more realistic than the other. Also, it can be stretched out longer than the former, possibly lasting years if need be. At the same time it can be resolved relatively quickly if the couple could work out rather well. It will need to be resolved at some point, but don’t force it; this one has the possibility of quickly becoming too cutesy if done wrong.
A third option is when the hero is doing something to remove an obstacle, but falls in love with the person he's doing the quest with. This has the advantages of both story lines, as well as contrasting the two loves. It also has an additional conflict line; not only must he succeed in the quest, but must also overcome his hatred for the person he's with. He must then make a decision over which love he ultimately goes for. This can be a fun with, especially if there are obligations that conflict with loving who he is with.
Establishing the obstacle and showing the penalty for ignoring or losing against it is just the first act. The second act is when the obstacle bares its teeth.