They had more time to develop their relationship.

This is a really big cliche and I have mixed feelings about it. When it comes to these kinds of romances I either love or hate them. A lot of the times they really come out of no where and are rushed, such as with Anastasia and Dimitri. They bicker for a long time but as soon as Anastasia puts on a pretty dress and changes her hair style they suddenly fall in love. Okay, I get the whole Dimitri is shallow and superficial, so he'll fall for Anastasia because of her looks, but why is Anastasia falling for him? They constantly fought and I saw no reason why she'd start falling for him AT ALL! Love-Hate romances usually rush into the characters falling in love without even explaining why and it's usually because they only have an hour and a half for the movie and it's hard to have it be more fleshed out.

With a TV show couple that is a love-hate relationship, it can be more fleshed out because, while an episode for an animated show usually can only be half an hour long, the show can be as long as it wants, so it doesn't have to be rushed. An example of this, while it's considered debatable on whether they're a couple, Misty and Ash from Pokemon are a love-hate relationship but they're much more developed and fleshed out than a lot of movie love-hate couples. They start off not being able to stand each other and all that constant bickering. But there is still some caring from one another, which causes them to lead to becoming mutual friends. As the show goes on they become great friends and it's hinted that they have feelings for each other because it's obvious to everyone except them. While Ash and Misty didn't end up together because of that whole making money by adding new characters that replace the only ones we know and love bull crap, TV show love-hate couples romance blooms much more naturally than a movies. Even after Misty leaves, they still give some hints that the two have romantic feelings for each other, despite the fact that the show tries to force the idea that they have romantic feelings for other characters when it's not believable at all. But I digress.

Movies can make good love-hate couples but they have to be very careful about it because it can often lead to it seeming rushed and unbelievable. There are cons to having love-hate couples in TV shows because a lot of the time it seems like it really DRAGS on and gets repetitive. While Ash and Misty for example still would bicker when they become great friends, they were also more friendly with each other and it wasn't as mean-spirited. But I should probably stop talking about Ash and Misty. Both movies and TV shows doing love-hate romances can be done wrong and be done right, but in terms of which one is usually done better, it's TV shows.

^agreed. I think if you're going to make a couple with as complex a relationship as a love/hate one, you really need to have a lot of time to develop it.

But TV shows or book series can also make the relationship seem pretty boring, I found the Ron-Hermione thingy of Harry Potter to be tedious and overall their relationship seemed slightly unhealthy.

Otoh while Arnold and Helga's interaction in their show didn't really change much through many episodes, I do think the show often tries to showcase the genuine feelings they have underneath the teasing and tough girl facade that Helga carries.

Yeah the time length, that's why most of my favorite animated couples are from TV series.

Pretty much what everyone else said.

and agreed about Ron and Hermione so much.

What everyone said.