Hello, could anyone tell me how/why this character on the show completed suicide?

Thank you.

Kutner is found dead of a self-inflicted gunshot wound in his apartment by Thirteen and Foreman in "Simple Explanation". Kutner left no reason for his suicide, causing Dr. House to suspect foul play. The show's producers have confirmed that his death was indeed a suicide.[4][5] Actor Kal Penn, who portrayed Kutner, had accepted a job at the White House as "a liaison connecting the Obama administration with arts and entertainment groups, as well as with the Asian-American and Pacific Islander communities.