As posted before, one of the two need to get the boy/girl, but in case two were close there's an "acceptance" scene, in which the other possible love interest sister will accept it.

(The loser gets Arianna.)

Hehe if only wasn't that she's their mother, I'd say that would be a winner and not a loser (I really like her character design)

...I was kinda hoping for "the catfight to end all catfights", but your solution is acceptable

What, they can't share?

Of course they can share their mother, I'm pretty sure that's what they grew up doing??