Thread:PetStarPlanet/@comment-5898621-20180301221919/@comment-5898621-20180629224230

I think it would be semi-canon. It has been stated that Luigi has a crush on Daisy, and the attraction appears to be mutual, though Nintendo never stated directly that they're in a relationship.

Having feelings for each other but not having an established relationship would make the pairing semi-canon. Yatori and LadyNoir are examples.