How does the theme of perseverance emerge within Erika's comments about Tanimura's break-up with his high school girlfriend?

Erika asks Tanimura if it has been difficult to be alone after being part of a couple for several years. Tanimura admits that it has been difficult and Erika goes on to suggest that perhaps these types of tribulations are necessary during one's youth in order to ensure the strength needed to live a long life. Erika says that struggle is a part of growing up "the way surviving hard winters makes a tree grow stronger, the growth rings inside it tighter" (59).