It's probably a simplistic answer💦
But headcanon that I like most, and I also have read from some fans, is that both of them form this bond of trust and union. (And not only from a romantic point of view.)

Something that I really like from Kanata and Allen, is the development that was given them since DESIRE.
Kanata closed himself off to everything. And that Allen might be able to get just little closer with something they both share (passion for hip-hop). It's wonderful.

They're a fun dynamic. But they're also was a relationship that at the beginning was not reciprocal and seems superficial. And now, both show they respect each other and allow themselves to be closer (especially on Kanata's part).

And I want that side be exploited much more!! See how they can really form a bond where both trust on each other.