It is a suggestion of people you may know or know and also of people you do know that know others you may be interested in. It is a suggestion to let you know there are others you might want to communicate with.
To turn off Facebook M Suggestions, open Facebook Messenger, and then tap your profile icon. On iOS, it's at the top left of the screen, on Android it's at the top right. Scroll down and select the “M Settings” category. To get rid of M suggestions, just turn the “Suggestions” toggle off.
Facebook messenger their algorithm works just like the Facebook algorithm, for the suggested friends. it's suggest people based on who you have mutual friends with or if somebody checked in at your school and location data says you were at the school too.
While instructing Naruto, he tells him that it's a difficult ninjutsu to learn and even the Fourth Hokage couldn't do it. It was an obvious giveaway that Kakashi was aware Naruto and Minato were father and son.
Canonically, yes, Rin had feelings for Kakashi. It's nice to imagine a fairy tale ending where she falls in love with Obito, the guy who loves her and certainly deserves a win, but we see in Kakashi's back story that she was in love with Kakashi — or, at the very least, infatuated with him.