"没有永恒的朋友，只有永恒的利益." No lifelong friends but lifelong interest. Since young before primary school, I was a strong believer in friendship. I was always the first who initiated contact with friends after we graduate for a gathering and catching up. But to my dismay, a lot of time this kind of affection is one-sided. I was almost a bit jealous of friends who got into new clique to the new environment. It like I am having withdrawal symptom towards friends "moving on". After secondary school, I already understand there is almost no friendship that will last forever. So I tell myself, 朋友是阶段性的。And after the army, I understand that friend is mutually beneficial and you are automatically excluded when you are no longer useful. 朋友是互相利用的。 Over time, from extorvert, I became an introvert. Excluding myself from gathering, get together, almost like social withdrawal.