Is it permissible for a young man to express his longing for his male friend, or is the word "longing" (اشتياق) specific to women or relatives?

"Longing" (shawq) is a high degree of love. It has been mentioned in the Sunnah, in the words of the Salaf, and in the Arabic language as being applicable to various things that souls yearn for and hearts long for, such as longing to meet Allah the Almighty and gaze upon His Face, longing for prayer, and longing to see friends or imams. Therefore, "longing" is not confined to longing for women. There is no harm in saying about a friend, "I long for him," meaning intense love for him and eagerness to see him, as long as it does not imply a corrupt meaning.