To the broader question of whether this has something to do with your bond with your husband, I suspect the answer to that might also be yes. (I wonder if you'd have the same rate of success conducting the test with someone other than your husband.) This leads us to the question: How does ESP work? Since no one really knows the answer to that, I'll give you my theory.
Each of us has our own unique psychic vibration frequency, which arises deep out of our consciousness (or spirit or soul or whatever you want to call it -- whatever makes us unique). Everything has such a frequency and they are all a part of the great universe of frequencies, or universal "mind." ESP, clairvoyance, telepathy, remote viewing and other modes of psychic phenomena are instances in which an individual's particular frequency is able to "tune in" to other frequencies and thereby perceive another's thoughts, feelings or actions.
Where one or more individuals' frequencies are somewhat in sync, this can result in the kind of bond that you describe with your husband. This closeness or similariities in frequencies is what might have attracted you to each other. Or, with some couples, this frequency synchronization can occur over time. I suspect that it's such synchronization of frequencies that accounts for the remarkable telepathy often exhibited by twins and by many parents and their children.
Again, this is just a theory and I don't think we have the scientific instrumentation yet with which to prove it. You can read more in my article, "The Psychic Symphony."