In high school, we studied the different types of conflict (person-to-person, person-to-self, person-to-environment). In the seminar, the speaker suggested that the most potent conflict was person-to-self. As a reader, that is sometimes true for me. However, my personal favorite is person-to-person conflict -- when the longings and desires of characters meet head to head. So I guess it's a combination of person-to-person and person-to-self.
I think love triangles came to be because of this combination. So many writers (too many, imho) seem to find a love triangle as the quickest way to boost tension. However, if it's not done well, all it does is weaken the MC (again, jmo). The speaker in this seminar gave a wonderful reason for that -- she said that a true love triangle needs to have conflict between all three characters. So, for example, the situation in Anna and the French Kiss, where Etienne has a girlfriend who's off-stage for pretty much the entire book, isn't a true triangle -- because there's no interaction between Anna and the other girl.
I find that an interesting idea. The speaker clarified that it didn't have to be romantic tension between all three -- but she said that if tension only existed along two of the three sides, it wasn't a true conflict. I think this is an important point -- too often, triangle tension (for lack of a better term) seems to focus around romance, when sometimes it would be better without that element. And writing that kind of love triangle is truly challenging (and when done poorly, it can bomb dramatically). Also, when I look at some of the books where I've liked the relational dynamics, I've noticed that, to a certain extent, there's tension between all three characters (whether romantic, or not).
An example (without spoilers, btw): In Divergent, the MC has tension with two of her leaders -- Four and Eric. The two leaders also clearly have conflict with one another (though we don't know why until the end). It's a very good use of triangle conflict, imo, and it adds a great deal of tension to the story. There are other pairs of tension, as well -- and at least one other triangle.
Another example (also without spoilers): In Matched, the MC has tension with Ky and with Xander -- and there is some tension between Ky and Xander, as well. It's not as obvious as the triangle in Divergent, but I think it's there (at least a hint of it). The conflict in this story came more from individual-society, I think, and it's an interesting study in how tension builds and what makes for the strongest tension.
What works best for you? What kind of tension do you prefer in your reading? Is it the same as what you prefer as you write? What's an example of well-done tension?