难解难分，难分难解

nánjiě-nánfēn, nánfēn-nánjiě

(1) [be inextricably involved]∶形容争斗的双方实力相当, 胜负未决, 难分高下

(2) [be sentimentally attached to each other]∶也形容情意绵绵, 情感深厚, 难以分离