Theme-related Expressions
A bosom friend afar brings distance near．
海内存知己，天涯若比邻。
A friend in need is a friend indeed．
患难见真情。
A friend is easier lost than found．
朋友易失不易得。
A life without a friend is a life without a sun．
人生没有朋友，犹如生活没有太阳。
A man is known by his friends．
视其友可知其人。
A true friend is a single soul dwelling in two bodies．
挚友同心。
Birds of a feather flock together．
物以类聚，人以群分。
buddy （非正式）伙伴(https://www.daowen.com)
companion 同伴
company 陪伴
competitor 竞争者
compromise 妥协
empathy 共情
foe 仇敌
frenemy 友敌，腹黑友
intimacy 亲密
loneliness 孤独
opponent 对手
peer 同龄人
reciprocity 互惠
reconciliation 和解
reliability 信任
rival 对手