_{[ Well, yeah. Karamatsu can agree that it sucks when friendships don't work out, or they leave, and you're sad, but..
Like always in regards to stuff like this, he does try to think positively when it comes to having friends. After all, loneliness is one thing he is terrified of. ]}

Not all friendships end up this way.. some can be very successful, and that is why you need to branch out and make more friends! If he left you important things, he must have cared a lot for you too.

It is okay to be sad about it.. like I said.
_{[ what a hypocrite... Karamatsu also hates feeling sad. ]}