When Rosalina appears for first time in the blooper, she's partially disappears for a few seconds due to a glitch that SMG4 didn't notice before he uploaded the video on a Monday evening as he was tired. So he only saw it the next day and then told his fans to ignore that part of the blooper.
She devotes some of her time to "Story Time" where she and dozens of lumas go inside a little house on her space ship and she reads stories to them (mostly gay/perverted stories like "Everyone Poops" 50 Shades Of Gray" and "Twilight", also stating that the lumas are partially gay and/or perverted).
Mario instantly fell in love with Rosalina upon meeting her, and decided to stay on the Comet Observatory forever with her and Spaghetti, only to freak out when he finds out that she has no idea what spaghetti is. However, he is still in love with her, and even has her phone number to talk with her. It's actually pretty sweet, especially when you remember it's Mario.