Vやる and Vよる are used to express a speaker's strong feelings, such as surprise or contempt, when the subject is neither the speaker nor the listener (a third-person subject). There is no such a grammar point in standard Japanese.
|English||He got married finally.|
|English||She was dumped again.|
|English||I wonder what he was doing here.|
やる vs. よる
In general, Vやる is used by women and Vよる is used by men, but women could use Vよる if they want to show stronger emotion.
やる/よる vs. はる
You may notice that the usage of Vやる and Vよる is similar to Vはる. However, it should be noted that Vはる is usually used when referring to strangers, people of higher status, or people you respect, while Vやる and Vよる are used for family members, close friends, or inferiors.
The feelings that Vやる and Vよる can express
While Vやる and Vよる can express speaker's feelings such as surprise and contempt, there are cases where they do not imply any strong feelings.
|English||Yesterday, your grandma was sleeping in the park.|