Most Helpful Guy
Because they think its the nicest way to let someone down.
Most Helpful Girl
He really likes you and respects you as a person, but decided he's not interested in pursuing a romantic relationship with you at this time. He doesn't want to lose your friendship in his life, and hopes you can still be friends. It's totally okay if you decide you're unable to maintain a friendship with him, your feelings are your own and you're under no obligation to remain in contact with him. I think he sounds like a stand-up guy, coming to your house to discuss this in person. Most people these days don't do that, and in my opinion, it shows how mature he is. Everyone could use a friend like that :) Take care!