No, there are several theories about it. It might be a form of jealousy, or a genuine hormone generated problem. I went to a very interesting lecture last year on pain that did active cat scans on close partners when one was subjected to pain, the scan of the partners brain showed an identical response! 'There are more things in heaven and earth than are dreamt of!'
That reminds me - went to Hamlet at RSC the other week and I heard quote after quote after quote! Did Shakespeare really say everything first? It certainly seems so (As You LIke It provides most of the rest!)