In condensed matter systems we can have paired quantum states, for instance vortex-antivortex pairs and Cooper pairs, etc. How do the partners within each pair recognize each other and stay together (or do they?) as long as it is below the critical temperature?
To be precise, suppose we have two pairs $A$, consisting of $A_1,A_2$ and $B$, consisting of $B_1,B_2$. What is the thing that determines the pairing? It seems that nothing can stop us from identifying $A_1,B_2$ as a pair.