Yes but that's selfish and that's his point. You're allowed to be sad, but the person in the most pain is your best friend, and they can't get over you if you're still trying to be in their life. They deserve time away and if they clearly don't want to be found because they're trying to heal from heartbreak, then as a best friend, you're supposed to allow them that
The least you could do is to leave them alone so they could get over you in their own terms. You tryna meddle back into their life would only make them feels miserable. The thing is here, that blond is throwing himself in a pity party when said friend left him for good so he could move on. Ask yourself, can you heal your heart knowing the person that you like rejected you and is showing interest in someone else all the while still be in a close proximity with you? Can you act like your feelings never happened? Yes you cant force your feelings onto someone else, but its the same goes for them needing to distant themselves from you after being rejected. So blond guy got clocked by ML in the head was well deserved for acting the way he is. Let the friend go cause theres someone else out there who can make the friend happy.
It kind of bothers me that he can't "miss" his best friend, or feel worried or sad that his friend suddenly left him unless he loves him. Like when the ML says that "if he doesn't have feelings for him," he should just leave him alone and forget, but like if my best friend just suddenly confessed to me and left (and I didn't have feelings for them), I would still want to find them and talk to them.