I saw the "shipping Cube with others" confession and had to add my own two cents.
I do like experimenting with what-if relationships, but when it comes to Sad Cube I find myself having a hard time thinking about how a relationship with a corrupted shape, especially someone who actively hurt Cyan Square would work out.
Close to Me indicates that Cyan Square is the closest being to Sad Cube, and that Sad Cube absolutely treasures their friendship above all else. Everything Sad Cube does in that song can be attributed to wanting Cyan Square to get closer them. Heck, the whole "crawling towards Cyan Square" part is dramatic as frick.
If you were to remove Close to Me, I most likely would have went, "Oh, their friendship is adorable," but because it exists I went, "Ohhh, they're THAT close."
So, thinking of Sad Cube ending up in a relationship with a corrupted without at least Cyan Square's approval, feels like a disregard to the whole thing that went down in Close to Me.
In short, I can't easily imagine Sad Cube in a relationship with a corrupted, because Close to Me has such a powerful impact on the story.
I'm not asking for more people to ship P1 x Cube (Blue Squares, as I dub them), just asking to not downplay their tight-knit friendship, especially in the presence of Close to Me.