[ Yu considers this quietly, thinking furiously. He has no doubt Dipper would be hurt by his own twin sister not remembering him, but would also very likely realize the same thing he has: their memories have been steadily going missing, and Mabel has lost all her memories of Dipper.

Thinking he'll have to text his friend as soon as he and Mabel part ways (or as soon as he gets a free moment if they don't), he decides to explain. ]

I'm sure he'd appreciate it if you did. Dipper is actually someone pretty special to you, Mabel. There's something going on right now. I'm not completely sure, but I think we're losing our memories because of something strange going on.