wall·flow·er
/ˈwôlˌflouər/
In social situations, a wallflower is a shy or unpopular individual who doesn't socialize or participate in activities at social events. He or she may have other talents but usually does not express them in the presence of other individuals.

Rose doesn't understand. Why would she care about other ponies? Friendship may be a big part of the society, especially with the new Princess and all, but what does it have to do with her? Two friends are enough, and so what if she doesn't exactly know little things like their favorite color, or their hobbies outside of work, or their birthdays...

Well, maybe she does have a few things to learn.

(Teen for some language)