Who is Tatyana Larin from Eugene Onegin and what is their importance?

Tatyana is the young girl, who falls in love with Eugene. Eugene, however, isn't interested. When Eugene goes away, Tatyana immerses herself in getting to know him... the things that interest him, the books he reads, and the notes he's left behind inside of his books. Unfortunately, her parents require her to marry someone she doesn't love, and Tatyana does as they wish. When Eugene returns the tables are turned, and although she loves him, she will never betray her husband.