Social anxiety: Some college boys may feel insecure or shy, and feel nervous or uneasy about interacting with girls. This kind of social anxiety may make them choose loneliness instead of facing the pressure of interacting with girls.
Economic pressure: during college, many boys may feel great economic pressure because of high tuition and living expenses. In this case, they may prefer to save money rather than spend too much money on dating and communication.
Academic pressure: College studies are often very heavy, and many boys may feel that they can't spare time and energy to associate with girls. Besides, they may want to succeed in their studies, so they don't want to be distracted.
Love concept: Some boys may be skeptical about love, or think that love is not the most important task in their college life. They may be more concerned about their hobbies and personal development than looking for a lover.
Social circle: Some boys may feel that their social circle is not strong enough, or they may not know the right girls. In this case, they may prefer to wait rather than look for love objects casually.
In short, everyone's situation is unique, so these reasons may apply to some boys, but not to all boys.