It can help tremendously to get along and to fully desire working together and to have mutual goals. However, I disagree with your belief about it being the 'most important quality.' There are simply so many complex factors involved in successful pairs partnerships. Skaters who don't particularly like each other have been known to put their differences aside and commit fully to each other for the greater good. Marissa Castelli & Simon Shnapir come immediately to mind as a pair team who couldn't stand each other personality-wise. But they purposely worked it out and decided to stay together for the longer haul, and they ended up going to the Olympics together, no matter that the partnership ended immediately afterward.
Later, I think Mervin & Marissa got along fairly well in the beginning, but the frustrations connected with their technical struggles and citizenship issues apparently led to their camaraderie breaking down. Ultimately, Marissa seemingly (from something she said in an interview) never adjusted to having a different partner who was not as tall as Simon. Still, M&M were sublimely smooth, with great style, speed, SS, and exciting potential. The bottom line is that they did not have good luck, and they never figured out their technical snafus.
In addition, as it turns out from what we've subsequently heard from Aljona, her partnership with Robin was mainly a professional relationship. They were apparently not that close otherwise. They had different personalities, differing cultural backgrounds and in the beginning different languages, so the communication between them developed slowly. They were bound together chiefly by the fact of how good they were together on the ice, and how deeply they desired to achieve the same goals (Olympic medalists, 5-time World champions, GPF champions, etc). They also stuck together through the difficult passage of dealing with the ostracizing their coach, Ingo Steuer, suffered at the hands of German fed and others harboring jealousies and/or ruffled feathers because of Steuer's prior forced association with the Stasi.
I'm sure there are plenty of other unique examples regarding teams who didn't necessarily get along well, but who excelled in their on-ice partnership. I agree that statistically better results likely predominate with pair teams who actually like each other.

In the case of Trennt & Evelyn, there's no doubt that they get along well, and perhaps they will stick it out and improve. In the past couple of seasons, they benefited from the retirement of D/R, and from the problems the aesthetically brilliant Cami/Drew have suffered with lack of consistency, and trying to master more technical difficulty.
We never know what will end up happening. But as it currently stands, I think the drawbacks I mentioned earlier that Trennt/Evelyn face, may make it difficult for them to advance as far as Trennt might be able to advance with a partner of Kirsten's caliber. Still, it is what it is, and I do agree as I already said earlier that pursuing a new partnership takes time and care. What Kirsten and Trennt have invested in their current partnerships is a lot, and not to be scuttled lightly. However, Kirsten & Michael are more successful, whereas Trennt & Evelyn might mutually be able to find better partnership options where they could possibly go farther than their current prospects together indicate. I have to blame the original poster who suggested a Trennt/Kirsten hookup!

It just seems like a delectable match.

Eh, but I know fanciful matches in our heads don't mean very much in the real world, especially when the odds are against such matches materializing.
BTW, simply lacing up boots and getting out on the ice is a gamble in and of itself.