Me and my sister discussed this a while ago with a post on the Nano forums, and with April Camp-Nano coming up, we've been discussing it again. Sadly, I can't find the thread where the question was posed to a wider audience (although it was specifically regarding teen fiction), so I assume it was before the last forum wipe. Anyhow, the three points which keep cropping up weren't what I expected when we started asking people this question, so I thought they would be good to share.
There's a certain historical romance author, who I shan't name, whose books all follow a formula something like this:
- Character A meets Character B
- They fall in love
- A develops some misconception about B that leads to A thinking they can't be together
- Tension and awkwardness escalates in their interactions until a confrontation, where they break up
- A has a revelation that they were wrong all along
- A and B talk things over, and get back together
Conflict caused solely by miscommunication is incredibly frustrating because it is so easily solved. Either the reader knows exactly how to fix it, or as soon as the solution becomes apparent, the reader starts asking why the characters didn't just talk it over as soon as the conflict began.
In the interesting of not making your readers frustrated with your novel - and also possibly hate your characters in the process - I would avoid this type of conflict at all costs.
Rational decision making
A very surprising consensus in this discussion is, "I don't want to read about teenagers who go out and get trashed and sleep with a guy and then regret it later, or about teenagers who don't tell their parents that their boyfriend is a werewolf, or teenagers who decide to go and fight demons with little to no martial arts experience, or teenagers who let them. I want to read about teenagers who go to a party and have a great time with their friends, who confide in their parents as soon as something bad happens, who don't go into situations without being prepared."
Basically, the reader becomes frustrated when problems arise from decisions that that know are poor as even as they're being made. If you're yelling at the character, "Don't do it!" and the character does it anyway, you lose a little bit of the connection to the character - they become less realistic, and less relatable.
It could also be a sign of poor plotting if your characters have to make these bad decisions to further your plot. The challenge is to make a good plot which still has enough conflict to keep people interested and then keeping your characters in that conflict while at the same time, making rational, sensible decisions.
There's a lot of complaint out there about love triangles. The problem - at least as I understand it - is that they very often centre around a girl who has to choose between two guys: one who is often a long-time friend or even boyfriend, who is sweet, kind, and has a lot in common with the girl; the other, who is dark, brooding and mysterious, with unpredictable mood swings, some sort of 'dangerous' backstory, and a lot of chemistry. And of course, the girl chooses the second option.
While no-one is going to argue that people in love always make rational decisions, this comes back to the previous point. There is very rarely a love triangle where the central character makes a genuine decision - nine times out of ten, the reader is sure that they will choose angsty-and-brooding over sweet-and-friendly. And when you know that angsty-and-brooding is so much worse, and is just going to screw up the character's life for the next however-many books, this is a problem.
Having written these out, I realise that basically, what makes a good novel comes done to this: relatable characters who make decisions which make sense, and strong plot which doesn't require contrived action to propel it.